My most recent check-in changes the hook_fb API. I have a feeling not many users are implementing their own hook_fb, so I don't expect this to inconvenience anyone.

If you are, the new parameters are:

hook_fb($op, $data, &$return)

$op will tell your hook what is expected of it. See fb.module for the list of ops.

$data is an array containins a variety of things, depending on the $op. Most importantly, $data['fb_app'] and $data[$fb] will be set when these are known.

$return is a data structure which your app can set, for those ops which expect a returned value.

The important thing to note is that $fb_app is not longer passed in, find it in $data. And the order of $data and $return parameters has changed.