Index: includes/common.inc
===================================================================
RCS file: /cvs/drupal/drupal/includes/common.inc,v
retrieving revision 1.954
diff -u -p -r1.954 common.inc
--- includes/common.inc	5 Aug 2009 15:58:34 -0000	1.954
+++ includes/common.inc	5 Aug 2009 17:16:51 -0000
@@ -3587,6 +3587,13 @@ function drupal_cron_run() {
   // Allow execution to continue even if the request gets canceled.
   @ignore_user_abort(TRUE);
 
+  // Prevent session information from being saved.
+  drupal_save_session(FALSE);
+
+  // Force the current user to anonymous to ensure consistent permissions on
+  // cron runs.
+  $GLOBALS['user'] = drupal_anonymous_user();
+
   // Try to allocate enough time to run all the hook_cron implementations.
   drupal_set_time_limit(240);