Index: includes/batch.inc
===================================================================
RCS file: /cvs/drupal/drupal/includes/batch.inc,v
retrieving revision 1.37
diff -u -p -r1.37 batch.inc
--- includes/batch.inc	26 Aug 2009 15:00:17 -0000	1.37
+++ includes/batch.inc	18 Sep 2009 14:58:29 -0000
@@ -450,7 +450,12 @@ function _batch_finished() {
     // multi-step form. We save the final $form_state value to be retrieved
     // by drupal_get_form(), and redirect to the originating page.
     $_SESSION['batch_form_state'] = $_batch['form_state'];
-    drupal_goto($_batch['source_page']);
+    if (empty($_batch['redirect_callback']) || $_batch['redirect_callback'] === 'drupal_goto') {
+      drupal_goto($_batch['source_page']);
+    }
+    elseif (function_exists($_batch['redirect_callback'])) {
+      call_user_func_array($_batch['redirect_callback'], array($_batch['id']), 'finish');
+    }
   }
 }
 
Index: includes/form.inc
===================================================================
RCS file: /cvs/drupal/drupal/includes/form.inc,v
retrieving revision 1.373
diff -u -p -r1.373 form.inc
--- includes/form.inc	18 Sep 2009 00:12:45 -0000	1.373
+++ includes/form.inc	18 Sep 2009 14:58:52 -0000
@@ -2902,8 +2902,13 @@ function batch_set($batch_definition) {
  * @param $url
  *   (optional - should only be used for separate scripts like update.php)
  *   URL of the batch processing page.
+ * @param $redirect_callback
+ *   (optional) Specify a function to be called to redirect to the progressive
+ *   processing page. By default drupal_goto() will be used to redirect to a
+ *   page which will do the progressive page. Specifying another function will
+ *   allow the progressive processing to be processed differently.
  */
-function batch_process($redirect = NULL, $url = NULL) {
+function batch_process($redirect = NULL, $url = NULL, $redirect_callback = NULL) {
   $batch =& batch_get();
 
   drupal_theme_initialize();
@@ -2918,6 +2923,7 @@ function batch_process($redirect = NULL,
       'source_page' => $_GET['q'],
       'redirect' => $redirect,
       'theme' => $GLOBALS['theme_key'],
+      'redirect_callback' => $redirect_callback,
     );
     $batch += $process_info;
 
@@ -2956,7 +2962,12 @@ function batch_process($redirect = NULL,
       // Set the batch number in the session to guarantee that it will stay alive.
       $_SESSION['batches'][$batch['id']] = TRUE;
 
-      drupal_goto($batch['url'], 'op=start&id=' . $batch['id']);
+      if (empty($redirect_callback) || $redirect_callback === 'drupal_goto') {
+        drupal_goto($batch['url'], 'op=start&id=' . $batch['id']);
+      }
+      elseif (function_exists($redirect_callback)) {
+        call_user_func_array($redirect_callback, array($batch['id']), 'start');
+      }
     }
     else {
       // Non-progressive execution: bypass the whole progressbar workflow
Index: includes/update.inc
===================================================================
RCS file: /cvs/drupal/drupal/includes/update.inc,v
retrieving revision 1.8
diff -u -p -r1.8 update.inc
--- includes/update.inc	18 Sep 2009 00:04:21 -0000	1.8
+++ includes/update.inc	18 Sep 2009 14:57:49 -0000
@@ -484,8 +484,11 @@ class DrupalUpdateException extends Exce
  *   scripts like update.php).
  * @param $batch
  *   Optional parameters to pass into the batch API.
+ * @param $redirect_callback
+ *   (optional) Specify a function to be called to redirect to the progressive
+ *   processing page.
  */
-function update_batch($start, $redirect = NULL, $url = NULL, $batch = array()) {
+function update_batch($start, $redirect = NULL, $url = NULL, $batch = array(), $redirect_callback = NULL) {
   // During the update, bring the site offline so that schema changes do not
   // affect visiting users.
   $_SESSION['maintenance_mode'] = variable_get('maintenance_mode', FALSE);
@@ -516,7 +519,7 @@ function update_batch($start, $redirect 
     'file' => 'includes/update.inc',
   );
   batch_set($batch);
-  batch_process($redirect, $url);
+  batch_process($redirect, $url, $redirect_callback);
 }
 
 /**