I really recommend Atlassian's FishEye (similar to trac) and Crucible (peer code review, with a friendly forum-like twist) - both of which are tightly integrated - for anyone into some serious teamwork-based coding on SVN, CVS, Perforce, or several other version-managed development.
Isn't reviewboard (http://code.google.com/p/reviewboard/) a very similar tool and supports more version control systems? Both tools also use django/python as well.
I have that down as reason #17 for leaving your corporate job. Seriously, though -- having your prize projects locked inside corporate walls is a huge problem, a real innovation-stifler. After many attempts to get a couple of my old projects open sourced, and then watching them deteriorate to non-use as they were passed on to others, I've all but given up on starting new projects at $JOB. Glad to see Google is still open to letting some things into the wild.
That Guido got to work on a version of Mondrian for the outside world indicates less about Google's willingness to open up and more about their need to please their superstar.
Fisheye: http://www.atlassian.com/software/fisheye/ Crucible: http://www.atlassian.com/software/crucible/
Atlassian's great about open source, and give free licenses to any non-profit or FOSS projects.