Actually, I have been thinking about moving the project at some point. Passlib is the first (and only) project I've setup at Google Code, and I've found Google Code's feature-set somewhat lacking. Even the source browser is awkward. The only positive collaborative feature I can even think of is the code-review tool.
That said, Passlib (and most of my other projects) currently use Mercurial instead of Git, so I'm leaning towards moving the project to BitBucket. When I get serious about the move, I'm planning to research the GitHub / BitBucket differences a bit further. That move may be for a while though, it's a big undertaking - converting to a different VCS (for GitHub), replicating the issue tracker, dealing with broken links around the web, etc.