Interesting, some leaked AMD Radeon 6970 (Cayman))results have surfaced,The Radeon HD 6970 (as it stands now in early days yet, without proper drivers and a proper release) looks like it will be at least 10% faster than the NVIDIA GeForce GTX480 (reference).
The card is scoring X12000 in 3D Mark Vantage, with a P score of P24499. Unigine Heaven results (1920 x 1200, 4xAA, 16xAF) giving a result of 36.6 fps.
Core speeds seem to be at around 800 - 900MHz, 6 + 8pin power requirements and an estimated TDP of 255W or more [via TweakTown via Zol.com.cn]