Should support most uses of facebook authentication.
If you are looking for developing a facebook app, you might be looking for the facebook api module (http://drupal.org/project/facebook_api).
Repeat, this will only let you login to a site using your facebook credentials, nothing else.
Update: I (halkeye) have moved on to other projects and am unable to support this. I'm open to another maintainer, or even community tested patches which I can try to apply, but since I am not running this anymore myself, I don't have time to maintain it.
Its also probably better to look at the new fbconnect module (http://drupal.org/project/fbconnect)