Found an article supposedly so I'll just share it.
Tech ARP : Haha... But let's be honest - the GeForce GTX 480 is more than just a little faster than the Radeon HD 5870. It's twice as fast at tessellation, and that's supposed to be ATI's pet feature!
ATI : You believe the drivel they write in their PR slides? Then you must be one of those Sarah Palin tea party nutcases. Doesn't matter anyway. It's only temporary.
Tech ARP : Why temporary? You can't be planning to launch a new series of graphics cards so soon.
ATI : No, but we will be fixing the tessellation performance real soon. You can count on a 3x increase in performance in the next Catalyst driver.
Tech ARP : How is that possible?
ATI : Simple. To reduce power and temperature, we turned off most of the tessellators in the Radeons. Why turn them all on when there are no games using tessellation? Remember - ATI loves polar bears. We will just fire them up in the next version of the Catalyst driver.
Source:
Tech ARP - ATI To Fix Poor Tessellation Performance