Originally Posted by noko
Doesn't 10.1 expose hardware tesselation, which could be used very beneficially in a game and make a extra feature for those with 10.1 cards without any or little performance lost.
Dx10.1 doesn't directly expose the hardware tesselation unit on ATi hardware(no caps bits, not in the specs). The capability is accessed using geometry shaders. Tesselation can also be done with geometry shaders on all Dx10.x hardware.
From the specs that's been released about Dx11, hardware tesselation will be included with the specs and all compliant cards will require it.