Django-facebook-profile is a project mainly written in Python, it's free.
Hooks a facebook user to the django user in a gae helper app.
This app is designed to be used on Google AppEngine with the django helper to use facebook for the authentication method instead of Google Accounts or Google's Oauth.
In settings.py in the MIDDLEWARE_CLASSES do not use
instead use 'django_facebook_profile.middleware.FBProfileMiddleware',
and add 'django_facebook_profile' to your INSTALLED_APPS
For best results, you will want to use the modified version of the helper here: https://github.com/dherbst/google-app-engine-django