Got XGL working on my Portege M200 (GF5200) without any hickups. KDE support is currently slightly lacking (it mostly works but needs to use gnome decorations for some reason) but on Gnome it works charmingly! eyeKandy here we come. Sadly, I did not get it to work on on my Radeon desktop. But hey, GF cards are cheap ;)

Update: For people refered here by Google: check https://wiki.ubuntu.com/XglHowto but be warned that you will likely have to use the gnome decorators and parts of the Kicker wont work very well. However it is not very hard to get working on Geforce cards. Good luck!