Currently at work, we use CVS. It works, just as it does for most of the open-source projects around. It's got some warts, and some things that I don't like about it, but we deal with them.

I know one of the developers at [link|http://www.collab.net/|collab.net], which is building the Subversion project you mentioned. As I understand it, that project is currently in some form of alpha stage (I don't stay current on the project because I don't use it), but they're due to do a final v1.0 release sometime 1Q or 2Q this year.

I'll definitely check it out (no pun intended) at that time, and see if we can't replace CVS here at work.