Has GNOME2 been forked?
The first project to fork GNOME2, EXDE, did not suceed. According to our own blog: the exde project died. This was supposed to be the "fork" of GNOME2, but it never became anything useful.
Fortunately, the old components are still being updated, and there is still hope. The plan is to keep them around for a while, being updated to the new technologies in GNOME3 (this has already been mostly done), and given a few new features as well.*
The better solution is to "fork" this newer code.
**As mentioned by Wojox (I implied this but didn't state explicitly), the fallback mode of GNOME3 is actually the panel, and this will be maintained for a while. It is also the "newer code" that I was referring to.*
Mate:
As mentioned by Perberos, there is now the Mate Deskstop, which is doing pretty well and being picked up by some distributions.
I've started to make a fork of GNOME2. It's called Mate (MDE: Mate Desktop Environment).
http://matsusoft.com.ar/projects