Works great ... but no ATI 3d.
libdrm, mesa, libgl, ati-dri and xf86-video-ati need to be rebuild to use dri2
The new kernel seems to work just fine on all my machines, however there is no kms love.
Booting without recompiling anything makes xdriinfo say there is no dri acceleration and xvinfo says there are no xv capable adaptors, however all apps seem to work smoothly (didn't test video).
Recompiling libdrm and friends from abs (as explained in the wiki) makes xv work but no dri or kms, when trying to modprobe radeon the following message is issued:
FATAL: Error inserting radeon (/lib/modules/2.6.33-ARCH/kernel/drivers/gpu/drm/radeon/radeon.ko): Unknown symbol in module, or unknown parameter (see dmesg)
Checking dmesg shows:
radeon: Unknown symbol drm_vblank_cleanup
However the system still boots and starts X without hangups so not a big show stopper.
I'll just wait for mesa and friends to catch up and I'll give it another go (this shouldn't take long I guess).