I've gotta come out and say how impressed (and surprised) I am with the new Catalyst 11.11 drivers. All of a sudden, Eyefinity is cake to set up and works excellent. I did a fresh install of Ubuntu 11.10, ran software updater, and then installed the Catalyst drivers using the Catalyst Install Manager (didn't need to build the packages). Boom, things work fine, even with Unity 3d!
Some slight issues still there:
-The Catalyst Control Center still crashes on me when making changes to the monitor configuration, but if I run it from the terminal (sudo amdcccle), it works fine.
-Manipulating the ordering of the monitors in CCC can still easily result in your monitors being offset by a few vertical pixels (you'll see it in xorg.conf), but you can just keep adjusting them in the CCC until they all are begin at 0
-Still need to uncheck sync to vblank in the compizconfig-settings-manager, or dragging windows and other effects are dog slow in Unity3d
-Still no Bezel Compensation support. I wonder if this could be emulated by making a larger than typical virtual resolution (matching the total resolution in Windows after bezel compensation), and then leave gaps between the starting positions of each monitor in horizontal pixels
Still, Unigine Heaven looks tight in Eyefinity here in Linux. Oddly, on my HD 6950 2GB, enabling the Ambient Occlusion option in the benchmark annihilates my FPS, even more so than tessellation. Gonna try some other games, and such, and maybe some Wine gaming.