ATI keeps releasing new versions of its Catalyst drivers suite now up to version 6.9. There is a huge list of fixes and known issues that can be read on the posted release notes. Performance improvements should not be expected other than in 3dmark (useless) and Doom 3 engine games. The drivers should support all cards starting with the older Radeon 9500 up to the latest Crossfire configurations on newer Radeon X1900 series boards.
*Doom3 performances improves up to 9.3% due to further OpenGL shader complier and transform engine optimizations on the entire Radeon® X1000 Series of products. The largest gains can be seen on Radeon® X1900 configurations at resolutions of 1600x1200 or higher.