Kenton Varda sent some information about the GAUGE engine project. Check it out:
A few months back, I announced the Grand Unified 3D Game Engine project
(GAUGE^3D) with the goal of creating a powerful open source 3D game
engine. At that time, the design of the engine was rather sketchy and
not as nice as it could have been. However, since that time we have
completely redesigned the engine to make it as clean and pleasant to
code as possible.
At this point I would like to invite anyone who has experience coding in C++ to join the project. There is alot to be done before GAUGE becomes usable to game developers or players, but with enough people working on it, it should not take long. GAUGE is free for anyone to download, use, modify, and distribute, and it will always remain that way. The source code is freely available to anyone who wants it as well. "