QuakeForge is always in constant development. Our development version has the latest features, but changes rapidly as bugs are fixed and features are added. Stable versions do not change significantly once released, though we sometimes make revisions of the stable branch to fix known bugs.
Newtree is the beginning of a new way of thinking about the source tree. The code in this tree is based specifically on Id Software's QuakeWorld 2.40 source code. There is no support for NetQuake/UQuake in this tree in order to keep it as bug-free as possible. Development is fast and furious, here's where the action is!
Our current version, considered beta but no longer in active development. We're fixing bugs in it as people report them to us, but all of the real work is going into newtree. If you find a bug, please let us know! After newtree above has hit its second milestone and supports single-player games, will probably discontinue support of this tree.
QuakeForge 0.1 is our initial offering to the public. It's not really for end-users, but served as a proof of concept that the Quake and QuakeWorld trees are more closely related than initial look would indicate.