ATI has now released the final revision of its Catalyst 4.9 drivers which should bring some performance improvement, especially in the new generation Radeons. Get them here.
Doom3 performance improves 10-15% on ATI RADEON™ X800 XT products when anti-aliasing is enabled. UT2004 performance improves considerably on the ATI RADEON™ 9500 PRO, RADEON™ 9700 PRO RADEON™ 9800 PRO and RADEON™ 9800 XT products. The benefit can be 25% or more in some circumstances, particularly at extreme graphics settings such as 6xAA + 16xAF.