Index: wp-includes/theme.php
===================================================================
--- wp-includes/theme.php	(revision 13052)
+++ wp-includes/theme.php	(working copy)
@@ -427,6 +427,8 @@
 		}
 	}
 
+	$wp_themes = apply_filters('get_themes', $wp_themes);
+
 	return $wp_themes;
 }