Index: modules/block/block.admin.inc
===================================================================
RCS file: /cvs/drupal/drupal/modules/block/block.admin.inc,v
retrieving revision 1.90
diff -u -p -r1.90 block.admin.inc
--- modules/block/block.admin.inc	10 Oct 2010 20:11:21 -0000	1.90
+++ modules/block/block.admin.inc	23 Oct 2010 03:19:04 -0000
@@ -286,11 +286,12 @@ function block_admin_configure($form, &$
     '#type' => 'fieldset',
     '#title' => t('Region settings'),
     '#collapsible' => FALSE,
-    '#description' => t('Specify in which themes and regions this block is displayed.'),
+    '#description' => t('Specify where this block is displayed.'),
     '#tree' => TRUE,
   );
 
   $theme_default = variable_get('theme_default', 'bartik');
+  $admin_theme = variable_get('admin_theme');
   foreach (list_themes() as $key => $theme) {
     // Only display enabled themes
     if ($theme->status) {
@@ -300,9 +301,18 @@ function block_admin_configure($form, &$
         ':theme' => $key,
       ))->fetchField();
 
+      // Use a meaningful title for the main site theme and administrative
+      // theme.
+      $theme_title = $theme->info['name'];
+      if ($key == $theme_default) {
+        $theme_title = t('!theme (default theme)', array('!theme' => $theme_title));
+      }
+      elseif ($admin_theme && $key == $admin_theme) {
+        $theme_title = t('!theme (administration theme)', array('!theme' => $theme_title));
+      }
       $form['regions'][$key] = array(
         '#type' => 'select',
-        '#title' => $theme->info['name'],
+        '#title' => $theme_title,
         '#default_value' => !empty($region) && $region != -1 ? $region : NULL,
         '#empty_value' => BLOCK_REGION_NONE,
         '#options' => system_region_list($key, REGIONS_VISIBLE),
Index: modules/block/block.api.php
===================================================================
RCS file: /cvs/drupal/drupal/modules/block/block.api.php,v
retrieving revision 1.13
diff -u -p -r1.13 block.api.php
--- modules/block/block.api.php	13 Aug 2010 12:25:14 -0000	1.13
+++ modules/block/block.api.php	23 Oct 2010 03:19:04 -0000
@@ -57,6 +57,7 @@
  *     - DRUPAL_CACHE_GLOBAL: The block is the same for every user on every
  *       page where it is visible.
  *     - DRUPAL_NO_CACHE: The block should not get cached.
+ *   - 'properties': (optional) @todo: Document me!
  *   - 'weight': (optional) Initial value for the ordering weight of this block.
  *     Most modules do not provide an initial value, and any value provided can
  *     be modified by a user on the block configuration screen.
Index: modules/comment/comment.module
===================================================================
RCS file: /cvs/drupal/drupal/modules/comment/comment.module,v
retrieving revision 1.906
diff -u -p -r1.906 comment.module
--- modules/comment/comment.module	20 Oct 2010 01:31:06 -0000	1.906
+++ modules/comment/comment.module	23 Oct 2010 03:19:04 -0000
@@ -402,6 +402,7 @@ function comment_permission() {
  */
 function comment_block_info() {
   $blocks['recent']['info'] = t('Recent comments');
+  $blocks['recent']['properties']['administrative'] = TRUE;
 
   return $blocks;
 }
Index: modules/dashboard/dashboard.module
===================================================================
RCS file: /cvs/drupal/drupal/modules/dashboard/dashboard.module,v
retrieving revision 1.40
diff -u -p -r1.40 dashboard.module
--- modules/dashboard/dashboard.module	21 Oct 2010 11:55:08 -0000	1.40
+++ modules/dashboard/dashboard.module	23 Oct 2010 03:19:04 -0000
@@ -90,6 +90,25 @@ function dashboard_permission() {
 }
 
 /**
+ * Implements hook_block_info_alter().
+ */
+function dashboard_block_info_alter(&$blocks, $theme, $code_blocks) {
+  $admin_theme = variable_get('admin_theme');
+  if (($admin_theme && $theme == $admin_theme) || (!$admin_theme && $theme == variable_get('theme_default'))) {
+    foreach ($blocks as $module => &$module_blocks) {
+      foreach ($module_blocks as $delta => &$block) {
+        // Make administrative blocks that are not already in use elsewhere
+        // available for the dashboard.
+        if (empty($block['status']) && (empty($block['region']) || $block['region'] == BLOCK_REGION_NONE) && !empty($code_blocks[$module][$delta]['properties']['administrative'])) {
+          $block['status'] = 1;
+          $block['region'] = 'dashboard_hidden';
+        }
+      }
+    }
+  }
+}
+
+/**
  * Implements hook_block_list_alter().
  *
  * Skip rendering dashboard blocks when not on the dashboard page itself. This
@@ -121,6 +140,10 @@ function dashboard_page_build(&$page) {
     // region into it.
     $page['content']['dashboard'] = array('#theme_wrappers' => array('dashboard'));
     foreach (dashboard_regions() as $region) {
+      // Do not show dashboard blocks that are disabled.
+      if ($region == 'dashboard_hidden') {
+        continue;
+      }
       // Insert regions even when they are empty, so that they will be
       // displayed when the dashboard is being configured.
       $page['content']['dashboard'][$region] = !empty($page[$region]) ? $page[$region] : array();
@@ -177,7 +200,15 @@ function dashboard_page_build(&$page) {
  */
 function dashboard_system_info_alter(&$info, $file, $type) {
   if ($type == 'theme') {
-    $info['regions'] += dashboard_region_descriptions();
+    // Add the dashboard regions (the "hidden" region should always appear last
+    // in the list, for usability reasons).
+    $dashboard_regions = dashboard_region_descriptions();
+    if (isset($dashboard_regions['dashboard_hidden'])) {
+      $hidden_region = $dashboard_regions['dashboard_hidden'];
+      unset($dashboard_regions['dashboard_hidden']);
+      $dashboard_regions['dashboard_hidden'] = $hidden_region;
+    }
+    $info['regions'] += $dashboard_regions;
     // Indicate that these regions are intended to be displayed whenever the
     // dashboard is displayed in an overlay. This information is provided for
     // any module that might need to use it, not just the core Overlay module.
@@ -312,12 +343,23 @@ function dashboard_form_block_admin_disp
     $form['block_regions']['#value'] = array_diff_key($form['block_regions']['#value'], $dashboard_regions);
     foreach (element_children($form['blocks']) as $i) {
       $block = &$form['blocks'][$i];
-      if (isset($block['region']['#default_value']) && isset($dashboard_regions[$block['region']['#default_value']])) {
+      if (isset($block['region']['#default_value']) && isset($dashboard_regions[$block['region']['#default_value']]) && $block['region']['#default_value'] != 'dashboard_hidden') {
         $block['#access'] = FALSE;
       }
       elseif (isset($block['region']['#options'])) {
         $block['region']['#options'] = array_diff_key($block['region']['#options'], $dashboard_regions);
       }
+      // Show hidden dashboard blocks as disabled on the main block
+      // administration form, so that they are available to place in other
+      // regions of the theme. Note that when the form is submitted, any such
+      // blocks which still remain disabled will immediately be put back in the
+      // 'dashboard_hidden' region, because dashboard_block_info_alter() is
+      // called when the blocks are rehashed. Fortunately, this is the exact
+      // behavior we want.
+      if ($block['region']['#default_value'] == 'dashboard_hidden') {
+        // @todo These do not wind up in correct alphabetical order.
+        $block['region']['#default_value'] = NULL;
+      }
     }
   }
 }
@@ -370,6 +412,9 @@ function dashboard_form_block_add_block_
  */
 function template_preprocess_dashboard_admin_display_form(&$variables) {
   template_preprocess_block_admin_display_form($variables);
+  if (isset($variables['block_regions'][BLOCK_REGION_NONE])) {
+    $variables['block_regions'][BLOCK_REGION_NONE] = t('Not currently on dashboard');
+  }
 }
 
 /**
@@ -431,8 +476,9 @@ function dashboard_regions() {
  */
 function dashboard_dashboard_regions() {
   return array(
-    'dashboard_main' => 'Dashboard main',
-    'dashboard_sidebar' => 'Dashboard sidebar',
+    'dashboard_main' => 'Dashboard (main)',
+    'dashboard_sidebar' => 'Dashboard (sidebar)',
+    'dashboard_hidden' => 'Dashboard (hidden)',
   );
 }
 
@@ -445,9 +491,9 @@ function dashboard_show_disabled() {
   // Blocks are not necessarily initialized at this point.
   $blocks = _block_rehash();
 
-  // Limit the list to disabled blocks for the current theme.
+  // Limit the list to blocks that are marked as disabled for the dashboard.
   foreach ($blocks as $key => $block) {
-    if ($block['theme'] != $theme_key || (!empty($block['status']) && !empty($block['region']))) {
+    if ($block['theme'] != $theme_key || $block['region'] != 'dashboard_hidden') {
       unset($blocks[$key]);
     }
   }
@@ -496,7 +542,7 @@ function dashboard_update() {
     parse_str($_REQUEST['regions'], $regions);
     foreach ($regions as $region_name => $blocks) {
       if ($region_name == 'disabled_blocks') {
-        $region_name = '';
+        $region_name = 'dashboard_hidden';
       }
       foreach ($blocks as $weight => $block_string) {
         // Parse the query string to determine the block's module and delta.
@@ -507,12 +553,7 @@ function dashboard_update() {
 
         $block->region = $region_name;
         $block->weight = $weight;
-        if (empty($region_name)) {
-          $block->status = 0;
-        }
-        else {
-          $block->status = 1;
-        }
+        $block->status = 1;
 
         db_merge('block')
           ->key(array(
Index: modules/node/node.module
===================================================================
RCS file: /cvs/drupal/drupal/modules/node/node.module,v
retrieving revision 1.1309
diff -u -p -r1.1309 node.module
--- modules/node/node.module	20 Oct 2010 08:15:33 -0000	1.1309
+++ modules/node/node.module	23 Oct 2010 03:19:04 -0000
@@ -2076,6 +2076,7 @@ function node_block_info() {
   $blocks['syndicate']['cache'] = DRUPAL_NO_CACHE;
 
   $blocks['recent']['info'] = t('Recent content');
+  $blocks['recent']['properties']['administrative'] = TRUE;
 
   return $blocks;
 }
Index: modules/search/search.module
===================================================================
RCS file: /cvs/drupal/drupal/modules/search/search.module,v
retrieving revision 1.365
diff -u -p -r1.365 search.module
--- modules/search/search.module	20 Oct 2010 01:31:07 -0000	1.365
+++ modules/search/search.module	23 Oct 2010 03:19:05 -0000
@@ -143,6 +143,7 @@ function search_block_info() {
   $blocks['form']['info'] = t('Search form');
   // Not worth caching.
   $blocks['form']['cache'] = DRUPAL_NO_CACHE;
+  $blocks['form']['properties']['administrative'] = TRUE;
   return $blocks;
 }
 
Index: modules/user/user.module
===================================================================
RCS file: /cvs/drupal/drupal/modules/user/user.module,v
retrieving revision 1.1211
diff -u -p -r1.1211 user.module
--- modules/user/user.module	20 Oct 2010 05:32:31 -0000	1.1211
+++ modules/user/user.module	23 Oct 2010 03:19:05 -0000
@@ -1273,10 +1273,13 @@ function user_block_info() {
   $blocks['login']['cache'] = DRUPAL_NO_CACHE;
 
   $blocks['new']['info'] = t('Who\'s new');
+  $blocks['new']['properties']['administrative'] = TRUE;
 
   // Too dynamic to cache.
   $blocks['online']['info'] = t('Who\'s online');
   $blocks['online']['cache'] = DRUPAL_NO_CACHE;
+  $blocks['online']['properties']['administrative'] = TRUE;
+
   return $blocks;
 }