Linux Mint 12 Lisa and onward (presumably) will use a combination of gnome 3 (or possibly a gnome 3 fork called cinnamon - more on that in a sec) and MATE (a gnome 2 fork). Mint has add MGSE (Mint Gnome Shell Extensions) to gnome 3 to make it look and act more like gnome 2 (it has a taskbar, a menu which is fairly similar to the mint menu, etc). MATE looks and acts just like gnome 2 (all of the "add to panel" things and themes work), but it is new and slightly unstable. Finally, Cinnamon, which is a fork of gnome 3 with the MGSE incorporated, might replace MGSE in the next release (13). It has one panel instead of two, and the menu is even more similar to the gnome 2 one. But it is still ALPHA software, so who knows where it will go.
Dell XPS 15 l502x - Debian Testing 64-bit NetInst Xfce, SolydX 64-bit Debian Testing, SolydK 64-bit SolydXK Testing
Old Gateway Pentium 4 Desktop - Arch Linux 64-bit Xfce and SolydX 32-bit Sid