WP-Cumulus has been ported to quite a few other platforms. I keep bumping into it, often on sites not running WordPress. I’ve given up trying to post about all of these spin-off projects, but this one feels a little special. Gautam Gupta has created a bbPress version. As far as I’m aware this is the first port to another Automattic project (I’m still waiting for a wordpress.com ‘port’, come on Matt ).
So, if you want your forum tags to fly like your blog tags, head over to http://bbpress.org/plugins/topic/bb-cumulus/ for the download.