ATI released new Catalyst drivers including an 11.6 video driver and a small SDK upgrade (from v2.4.595.10 to v2.4.650.9)
I'm testing them on my boxes now and have noticed an improvement to hashing, but only on the order of 1-2% at most.
Radeon 6950 starting with Cat 11.5 and SDK 2.4.595.10 to 11.6/2.4.650.9 went from 366 MH/s to 369 MH/s max.
Radeon 5770 starting with Cat 11.5 and SDK 2.1 to 11.6/2.1 went from 208 MH/s to 214 MH/s max.
Still have a few more cards to test. Has anyone else downloaded/tested them?