I've created a django-nonrel app on gae. Added a user (django.auth.models.User) with is_active, is_staff, is_suiperuser all True. On localhost I login successfully, but I fail to login on GAE after deploy (I've created the same user on GAE too and it can be seen on datastore view).
But when I try to login on http://.appspot.com/admin/ it returns "Please enter a correct username and password."
Nick and Elliot are right. You have to use manage.py remote createsuperuser