Most of ATI's partners will go for the overclocked version of the Radeon HD 2900XT cards and it might take up to two to thee weeks before you will be able to buy these faster cards.
We don't know how much ATI's partners want to push their R600 XT cards but you can easily go up to 850 MHz core with a reference cooler. With water 900MHz+ should be easy but at press time we don't have much details about the cards.
Obviously these cards will end up more expensive and we are not sure about their availability. This will make R600XT, Radeon HD 2900XT look better but most probably even the overclocked card won't be able to beat 8800 GTX at least not in most of the tests.
ATI's cooler is desperate for more heat pipes and the card itself definitely needs a water cooler to works on a safer working temperatures.
You know how it goes, with ATI you are doomed to wait one thing or another.