To follow up on Ron's response to Roberto, you might want to check out Perforce's
CVS to Perforce comparison. I also want to reiterate that the change to Perforce is motivated by purely technical reasons. I was one of the managers of the CVS tree, and I can say that the lack of atomic checkins is a huge headache. In order to keep the tree relatively clean, we had to resort to things like developer-based lazy branching, do very careful checking after landing branches to prevent silent merge deaths, and do poor man's atomicity with CVS tags. In CVS, before committing a major change, you tag before and you tag after so you can rollback, but in Perforce, it's just one checkin. Moreover, you can apply that checkin to multiple branches, which is something you can't do in CVS. I'm not saying that CVS is a bad system, and that it's not workable (as Roberto points out, Samba and Postgres are two examples where people are using it successfully). We just decided that the cost of maintaining a CVS tree is too high given the number of developers that we have. We have 40+ developers with commit rights on the tree. Samba has 20; Postgres appears to have 18. And yes, anon checkout via either CVS or Perforce is coming soon :).
