See also zsh, another great shell that gets little attention.
Recent versions of zsh (though not the version that ships with OS X) have a feature called vcs_info that will pull information from git, svn, cvs, hg, darcs, bzr (& more) for use in your prompt.
Here's a pic of it showing branch@revision status for svn repositories: http://tweetphoto.com/29802557
It does the same for git repositories as well and some other nice stuff.