diff -urp --strip-trailing-cr ../drupal-6.x-dev/modules/poll/poll.install ./modules/poll/poll.install
--- ../drupal-6.x-dev/modules/poll/poll.install	2009-01-06 16:46:37.000000000 +0100
+++ ./modules/poll/poll.install	2009-07-18 22:29:37.000000000 +0200
@@ -130,3 +130,21 @@ function poll_schema() {
   return $schema;
 }
 
+/**
+ * @defgroup updates-6.x-extra Extra poll updates for 6.x
+ * @{
+ */
+
+/**
+ * Fix cache mode for "Most recent poll" block.
+ */
+function poll_update_6000() {
+  $ret = array();
+  $ret[] = update_sql("UPDATE {blocks} SET cache = 2 WHERE module = 'poll' AND delta = '0'");
+  return $ret;
+}
+
+/**
+ * @} End of "defgroup updates-6.x-extra"
+ * The next series of updates should start at 7000.
+ */
diff -urp --strip-trailing-cr ../drupal-6.x-dev/modules/poll/poll.module ./modules/poll/poll.module
--- ../drupal-6.x-dev/modules/poll/poll.module	2008-12-18 16:46:20.000000000 +0100
+++ ./modules/poll/poll.module	2009-07-18 21:45:53.000000000 +0200
@@ -131,6 +131,7 @@ function poll_block($op = 'list', $delta
   if (user_access('access content')) {
     if ($op == 'list') {
       $blocks[0]['info'] = t('Most recent poll');
+      $blocks[0]['cache'] = BLOCK_CACHE_PER_USER;
       return $blocks;
     }
     else if ($op == 'view') {
@@ -776,6 +777,8 @@ function poll_cancel($form, &$form_state
 
   // Subtract from the votes.
   db_query("UPDATE {poll_choices} SET chvotes = chvotes - 1 WHERE nid = %d AND chorder = %d", $node->nid, $node->vote);
+
+  cache_clear_all();
 }
 
 /**