Let's not start a discussion on which DVCS is better, or I'd burn your ears off about all the ways each of those (as well as Bazaar, Arch/tla/bzr1, Arx, CodeVille, SVK, Monotone and BitKeeper) suck, suck badly or are the work of the devil. The official Python source repository will be Subversion for now (although it isn't officially my decision :). I encourage anyone to use a mirror of it in their own favourite VCS, and do their own development in it. 'tailor' is a nice tool if you care about having the full history (as I do) and you don't happen to hit bugs in it or the VCS. Do realize that the full history may be a burden, especially in DVCS solutions.

For what it's worth, rumour has it Subversion 1.5 or 2.0 will get actual branch tracking and full-history merging. If done properly (it's not done yet, so it's hard to say) it would reduce the advantage of the DVCS solutions by about half ;-P