Greetings to all!
I've decided to post another XGL guide for installing and compiling XGL.
The only real difference is that the guide sets all the libraries, includes, binaries, and sources, up under /opt. Basically, nothing really gets installed to /usr or /usr/lib (or even /usr/lib64, for AMD64 users), so you don't have to worry about prodding Fedora.
If something does bork, just 'rm -rf' everything under Opt. It will take XGL and everything (I do mean everything) associated with XGL with it. No more messing with removing RPM's, or as some of you may have noticed, playing with Control-Center which may/may not change the layout of your System->Preferences menu.
I personally think it's a much more tidy, and clean method of setting up XGL. Fedora isn't touched, so everything should be happy-rainbows even if you have to delete XGL. Anything not associated or built against XGL living under /opt shouldn't be aware that XGL even exists, so control-center and Package Updater shouldn't have to worry about RPM hell, as well as any programs you may compile against the Fedora base system shouldn't be affected.
I may or may not check into building some XGL RPM's that basically install everything under /opt, which should make RPM installation a little more sucsessful.
As always, post if you need help. I'll try and help you with any problems.