Index: modules/user/user.module
===================================================================
RCS file: /cvs/drupal/drupal/modules/user/user.module,v
retrieving revision 1.951
diff -u -p -r1.951 user.module
--- modules/user/user.module	30 Dec 2008 16:43:20 -0000	1.951
+++ modules/user/user.module	2 Jan 2009 17:46:36 -0000
@@ -1354,6 +1354,7 @@ function user_authenticate($form_values 
     if ($account) {
       // Allow alternate password hashing schemes.
       require_once DRUPAL_ROOT . '/' . variable_get('password_inc', 'includes/password.inc');
+      module_invoke_all('user', 'authenticate', &$form_values, $account);
       if (user_check_password($password, $account)) {
         if (user_needs_new_hash($account)) {
            $new_hash = user_hash_password($password);