The project is Arch (now Gnu Arch). It's a fairly small project now, with a dictatorship style of leadership, but it is already a very useful tool (version 1.1 is scheduled to release beginning of November).
Arch is a distributed version control system (self-hosting, of course), which is why so many people are able to contribute to it. Developers can make their own repositories and branches, make their changes, and have their work merged back into the main tree. Most developers set up their own "read-only" repositories, and submit bug fixes or new features by telling the lead developer which repository/branch/patch to merge from.
