--- drush-6.x-1.0-rc2/drush_pm/drush_pm.module	2008-05-19 04:06:58.000000000 +0200
+++ drush/drush_pm/drush_pm.module	2008-05-22 23:48:59.000000000 +0200
@@ -272,6 +272,12 @@ function drush_pm_update() {  
     
     $source = DRUSH_DRUPAL_ROOT .'/' . $project['path'];
     
+    // Themes are currently not handled; skip them (but give a warning message)
+    if ($project['project_type'] == 'theme') {
+      drush_print(t("Drush does currently not support updating themes; skipping !title.", array('!title' => $project['title'])));
+      continue;
+    }
+
     $skip_backup = module_invoke_all('drush_pm_skip_backup', $source);
     if (!count($skip_backup)) {
       $backup_dir = DRUSH_DRUPAL_ROOT. '/backup';