=== modified file 'includes/form.inc'
--- includes/form.inc	2009-04-11 22:19:44 +0000
+++ includes/form.inc	2009-04-23 21:32:24 +0000
@@ -973,6 +984,9 @@ function form_builder($form_id, $form, &
   if (isset($form['#type']) && $form['#type'] == 'form') {
     $cache = NULL;
     $complete_form = $form;
+    // Merge in default values.
+    // @TODO: remove once all core has been converted to form_ahah_callback.
+    $form_state += form_state_defaults();
     if (!empty($form_state['programmed'])) {
       $form_state['submitted'] = TRUE;
     }