if multiple placeholders exist create multiple aliases for a node

Greggles-

Please re-read the patch. I'm not concatenating....
The patch allows a node to have multiple aliases for each combination.
Your post would get two aliases:
g.d.o/paths/pathauto-i18n-integration
g.d.o/internationalization/pathauto-i18n-integration

I.e., if I return [cats] => array( 'blue', 'red', 'green') and my path is '[cats]/[nid]', then I would get three aliases:
blue/3
red/3
green/3

Likewise, if I had two arrays, i.e., [ognames] => array('circle', 'square') and my pattern was '[ognames]/[cats]/[nid]', I would end up with 6 aliases:
circle/blue/3
circle/red/3
circle/green/3
square/blue/3
square/red/3
square/green/3

This enables me to alter CSS classes in the template based on q[0] and q[1], customizing by the og or category that an item is being pulled up in.

I think this functionality would be useful for other people. I deliberately did NOT patch the placeholders for [cat] or [catpath], but implemented _pathauto_node with my own placeholders, for [cats] and [ognames], so as not to cause other side effects.

Sure thing, sample code as follows:

function mymodule_pathauto_node($op, $node=NULL) {
  static $groups;  //cache our list of groups in between calls for speed
  switch ($op) {
    case 'placeholders':
      $placeholders = array();
      $placeholders[t('[ognames]')] = t('The field_shortnames of the organic groups this post belongs to.');
      return $placeholders;
    case 'values':
      if (!isset($groups)) {
        $sql = 'select nid, field_shortname_value from content_type_group';
        $result = db_query($sql);
        while ($record = db_fetch_array($result)) {
          $groups[$record['nid']] = $record['field_shortname_value'];
        }
      }
      $results = array();
      if ($node->og_groups) {
        foreach ($node->og_groups as $gid) {
            if ($gid != 0) {
              $name[] = pathauto_cleanstring($groups[$gid]);
            }
        }
      }
      $results[t('[ognames]')] = $name;
      return $results;
    default:
      break;
  }
}

I've done something similar with [cats].

Our path is "[ognames]/[title]" for the purposes of this example.

So, in the head of page.tpl.php template, we then have:

<?php
$myq = split('/',$_REQUEST['q']);
$og = $myq[0];
?>
<style type="text/css" media="all">@import ""<?php print base_path() . path_to_theme() ?>/style.css";</style>
<style type="text/css" media="all">@import ""<?php print base_path() . path_to_theme() ?>/style-<?php print $og;?>.css";</style>

Ideally, we should filter $og to make sure it's valid and style-{$og} exists, but that would be another function call to get the group field_short_name values.

Voila! Based on the OG in the URL alias, I'm presented with a completely different look and feel for the exact same content.

So... if you'd like to move this over to the discussion at Groups, please do, I'll gladly join in there.
If there's another better way to do what I'm trying to accomplish, I would gladly try it out.

Also, the other big issue with this approach is the removal of aliases, but I think that's a bigger issue.