Index: modules/system/system.module
===================================================================
RCS file: /cvs/drupal/drupal/modules/system/system.module,v
retrieving revision 1.862
diff -u -p -r1.862 system.module
--- modules/system/system.module	15 Dec 2009 08:45:32 -0000	1.862
+++ modules/system/system.module	15 Dec 2009 16:24:21 -0000
@@ -2710,6 +2710,12 @@ function system_cron() {
     cache_clear_all(NULL, $table);
   }
 
+  // Force clear the page cache if automatic cron is enabled so that pages
+  // get a new JavaScript timestamp for the next cron run.
+  if (system_run_cron_check_access()) {
+    cache_clear_all('*', 'cache_page', TRUE);
+  }
+
   // Reset expired items in the default queue implementation table. If that's
   // not used, this will simply be a no-op.
   db_update('queue')