I contacted one of the developers (Casey Muller) a few days ago when I noticed the repository had disappeared. I'm quoting from his reply:

"""This is pretty lame, apparently it was really out of date and we're having trouble finding the resources internally to support it.

For now we're pointing people here: https://github.com/pythonforfacebook/facebook-sdk """

Although I think the sudden disappearance wasn't a smooth move, I guess the community will have to step up and maintain the library. Nothing wrong with that, it was open source to begin with.