If you like Gnome and have had trouble installing it on a mac, there is a work around, if you could call it that.
Since I need a windows environment on my iMac for work, I installed VMWare fusion 4. This provides a virtual environment into which you install windows (this was all very easy to do, trust me). Gnome installed easily as it would into any windows environment. Oh, and it works. No need to boot into windows, you simply open VMware and start a windows session. You have access to both the Lion and Windows OS and desktops!
The timing was good: a new iMac with Lion + version 4 of VMware + windows 7. Since I hadn't installed bootcamp yet, I didn't bother. No need with VMware (although it can work with bootcamp if you have that installed already).
Very cool stuff,
Phil