Since Python is Open Source are you looking at Per Force which you can use for free and seems to be a happy medium between something like CVS and something horrific like Clear Case?
No. The PEP is only about Subversion. Why should we be looking at Per Force? Only because Python is Open Source?
Perforce offers free licensing to open source projects.
I think anything but Subversion is ruled out because:
- there is no offer to host that anywhere (for subversion, there is already svn.python.org)
- there is no support for converting a CVS repository (for subversion, there is cvs2svn)
There *is* support for converting a CVS repository to Perforce .
Perforce is very good, stable, solid, reliable, good tools, etc. etc. but I'd tend to support SVN over Perforce for Python development. Perforce usage is quite different than CVS (would be a painful re-learning for old CVS-hands) and SVN tends to better support highly distributed development: most operations don't need to talk to the server, with Perforce (aka p4), almost *all* operations talk to the server. This can be somewhat mitigated with "p4proxy" (a tool that Perforce also provides) but people would be happier with SVN, I'd bet.
 It is a project called VCP. Some details here (I didn't look too hard): http://www.cpan.org/modules/by-module/LWP/AUTRIJUS/VCP-autrijus-snapshot-0.9...