If you just want to get started, check out Fandjango on github. Its a simple middleware layer that adds a facebook_user
attribute to the request object when the user is logged in, and sets it to None when they are not logged in. It also has an easy way to call the Graph API with the users' credentials.
Note: It only works on Facebook Apps. Websites using facebook connect use a slightly different protocol.
Also note: Any library that references 'pyfacebook' is using the old FB API and you should avoid that. The new one that uses the Graph API is python-sdk. You shouldn't use python-sdk either since its deprecated - thanks @pydanny. I haven't researched it, but facebook-sdk looks actively maintained.