The Mate Desktop Environment fork of GNOME2 was started by an Arch Linux user back in June, but it hasn't yet gained too much traction and is mostly just talked about on various forums around the web. It also hasn't been picked up by any distribution repositories at this point, but there is an AUR repository available for Arch Linux users.
The project overview is just: "MATE Desktop Environment, a non-intuitive and unattractive desktop for users, using traditional computing desktop metaphor. Also known as the GNOME2 fork."
So far the project is mostly about maintaining the GNOME2 packages, but there's talk of developing a new control panel and other original work to the project. Details on the project along with download instructions and other information on the Mate Desktop Environment can be found via this web-site.
While a lot of people dislike Unity and GNOME Shell right now, only time will tell whether the Mate Desktop Environment will succeed in maintaining the GNOME2 desktop.
Speaking of Unity, Mark Shuttleworth blogged this week about some of the Unity / Dash improvements for Ubuntu 11.10. In particular, Dash takes shape. There's numerous visual refinements, performance improvements, panel and dash advancements, and other work to further polish the Unity desktop beyond its rough shape it was found in when made the default desktop in Ubuntu 11.04. Unity 2D using QML is also taking shape for those upgrading to Ubuntu 11.10+ without proper 3D acceleration support in place.