Im using:
Ubuntu Edgy (6.10), 32bit
Gnome w/ Beryl under Xgl
ATi X800XT, fglrx driver
Well, a lot of ppl seem to have several problems with this combination, but nevertheless I had no problems at all so far. Beryl runs fine AND I can start OpenGL games, i.E. "Sauerbraten" runs fully accelerated, without the need of special hacks (like "nonXgl"). Also Nexuiz is accelerated - but all map textures are broken, everything looks weird, effects dont work well as it seems. Its the only GL-game I know where this appears.
This isnt a major problem for me - in a usual gnome session (regular X-Server without beryl), Nexuiz looks amazing. But if anybody knows a little trick I would be happy to hear ,-)
thanks