Arch

GNU Arch supports both distributed and centralized development. Developers commit their changes to an "archive," which may be local, and the changes can be pushed and pulled to other archives as the managers of those archives see fit. As such a methodology implies, Arch has more sophisticated merge support than CVS. Arch also allows one to easily make branches of archives to which one does not have commit access. This is only a brief summary; see the Arch web pages for details.

http://www.gnu.org/software/gnu-arch/