Index: includes/session.inc
===================================================================
RCS file: /cvs/drupal/drupal/includes/session.inc,v
retrieving revision 1.54
diff -u -F^f -r1.54 session.inc
--- includes/session.inc	6 Sep 2008 08:36:19 -0000	1.54
+++ includes/session.inc	7 Sep 2008 03:56:35 -0000
@@ -125,6 +125,14 @@ function sess_count($timestamp = 0, $ano
  */
 function sess_destroy_sid($sid) {
   db_query("DELETE FROM {sessions} WHERE sid = '%s'", $sid);
+
+  // Unset all of the session variables.
+  $_SESSION = array();
+
+  // Delete the session cookie. This will destroy the session, as well as the session data.
+  if (isset($_COOKIE[session_name()])) {
+    setcookie(session_name(), '', $_SERVER['REQUEST_TIME'] - 3600, '/');
+  }
 }
 
 /**