I've been considering what to do about the forum for the long run and one thought was to upgrade to phpBB3, but now I'm considering implementing it using the existing Hawkee framework. It could work much like status updates except posts will have titles and categories. This seems to make the most sense. I'd have to implement category pages as well as topic lists, but besides that the existing infrastructure should cover the rest.
I also cleaned up the private messages a bit. Eventually I'd like to completely redo those, but for now this will suffice.