It's totally unnecessary, unless we have a product that supports it.
Though it's kind of a given that ATI would go to Shader Model 3.0, given that the NV40 gains ~33% over SM2.x using SM3.0*; ATI may be very strong in DX9 and SM2.x in particular, but they can't afford to have nVidia getting the same (if not better) IQ with higher speed using SM3.0.
*Yes, it's a recalled patch, and yes, it's only in certain situations, but the code is rudimentary in FarCry and isn't incorporated into an engine written entirely in SM3.0. Not to mention that the Unreal 3 engine will use SM3.0, which means ATI
has to upgrade.