BitKeeper

The BitKeeper Development Platform provides powerful configuration management capabilities and workflow control. BitKeeper was designed to solve many of the scaling, performance, and merge problems that legacy SCM sytems repeatedly introduce.

BitKeeper was used for a short time as the primary SCM for the linux kernel. See http://en.wikipedia.org/wiki/BitKeeper Git was created by Linus Torvalds as a free replacement to BitKeeper

The BitKeeper home page is: http://www.bitkeeper.com/