I find it difficult to identify a tool that does good VCS as well as good team communication (ticket management, collaborative documentation etc.). It just makes so much sense to have them all "close together" in the same context. While the current BB issue tracking is fine, I find the Wiki to be too basic and cumbersome, esp. if you have non-techies in the project.
Have you taken a look at TeamBox yet? http://teambox.com It's on RoR, so not a natural candidate for your pythonic setup, but still would be a fantastic addition to bitbucket. I've been using it with my team and we all love it!
The prices on teambox.com are quite steep though. If you asked me, I would be happy to pay BB an extra few bucks on top of my normal BB plan, for having the opensource Teambox nicely integrated into BB.
What do you guys think? How large is the effort to integrate it?