If you’d like to get involved with bbPress, there a few places that are good to hang out.
Bug Tracker
We use a bug tracker called Trac which is the best place for us to have tickets to track bugs and enhancements. You can participate in a number of ways: “bug gardening” is basically going through tickets and making sure they have all needed info, are categorized and tagged properly. You can test patches that have been submitted and say whether they work or not. And of course you can give your feedback on the various proposals and idea, though for long-form discussion the mailing list might be better.
Mailing List
We have a mailing list called bbDev which gets SVN commit messages and is the best place to discuss things. Email etiquette applies: make sure to trim your replies, be polite, double-check your responses, and give people the benefit of the doubt.
Internet Relay Chat, or IRC
We have an IRC channel on Freenode called #bbpress. Here are some IRC resources, just follow those directions and replace #wordpress with #bbpress. Many people idle on IRC even when they’re not at their computer, so if you ping someone know that they might respond later. We currently meet on IRC at 2100 GMT on Wednesdays. You can convert to your local timezone here.