Index: modules/system/system.admin.inc
===================================================================
RCS file: /cvs/drupal/drupal/modules/system/system.admin.inc,v
retrieving revision 1.328
diff -u -r1.328 system.admin.inc
--- modules/system/system.admin.inc	13 Jan 2011 01:08:28 -0000	1.328
+++ modules/system/system.admin.inc	4 Feb 2011 16:00:03 -0000
@@ -2167,11 +2167,19 @@
     '#default_value' => variable_get('maintenance_mode_message', t('@site is currently under maintenance. We should be back shortly. Thank you for your patience.', array('@site' => variable_get('site_name', 'Drupal')))),
     '#description' => t('Message to show visitors when the site is in maintenance mode.')
   );
+	$form['#submit'][] = 'system_site_maintenance_mode_submit';
 
   return system_settings_form($form);
 }
 
 /**
+ * Flush all caches when changing maintenance mode
+ */
+function system_site_maintenance_mode_submit() {
+	drupal_flush_all_caches();
+}
+
+/**
  * Form builder; Configure clean URL settings.
  *
  * @ingroup forms