--- sites/all/modules/ubercart/contrib/uc_signup/uc_signup.orig.module	2009-09-09 03:50:32.000000000 +0100
+++ sites/all/modules/ubercart/contrib/uc_signup/uc_signup.module	2010-01-14 12:22:36.000000000 +0000
@@ -583,6 +585,10 @@
             if (empty($account->uid)) {
               $form_state['values']['mail'] = $mail;
               $namenew = preg_replace('/@.*$/', '', $mail);
+              // Remove + signs from username
+              $namenew = str_replace('+','',$namenew);     
               // From the email registration module:
               if (db_result(db_query("SELECT count(*) FROM {users} WHERE LOWER(name) = LOWER('%s')", $namenew)) > 0) {
                  // Find the next number available to append to the name