A week or so ago I managed to get Xgl working on a box at home using these instructions wtih an aging Nvidia card. I previously had issues getting it to work with an ATI card, but I think that had more to do with flgx and my rather old Radeon than anything else.
I was completely blown away when I started up XGL and enabled compiz for the first time. It brought an extra level of polish to the already amazing Dapper Drake. By default it enables several effects and features. Some are more whizzy than useful, but the alt-tab preview pane and expose-like features are quite useful. Less useful but still pretty are true transparency and the waving effect that happens when you drag a window.
That’s to be expected though. Xgl is still very much unstable and bleeding edge. Even if it’s not usable (for me) day in and day out, I think it’s a glimpse in to the future of desktop linux. The packages are available in the Universe repository for Dapper, but there are big warnings everywhere about their experimental nature.
I really hope that over the next six months Xgl matures and that by the time Edgy Eft is born Xgl will be ready for prime time, if not in the default install.