Rawhide contains and f19 will get Django-1.5 instead of Django-1.4.x soon. If you're not sure, if your package is compatible with Django-1.5, please change Requires: python-django to Requires: python-django14 and rebuild. If I don't hear anything against it, I can do the rebuild in the week after Apr 22nd.
Looking through https://docs.djangoproject.com/en/dev/releases/1.5/#backwards-incompatible-changes-in-1-5 I don't believe there's too much there that would present a problem for cobbler. The main one that could be a problem might be "Non-form data in HTTP requests", which I will need to test for. Overall, I do not believe that a strict requirement on 1.4 is required at this time.