the R300 is a 0.15-micron chip but it is also fully DirectX 9 compliant. Being DirectX 9 compliant means that the R300 pipeline is fully floating point from start to finish, which increases the transistor count of the chip tremendously.
From Anandtech's ATi 9700 preview (the R300 core).
Just as 3DLabs mentioned to us during our P10 briefing, in order to make the 3D pipeline entirely floating-point you need to be on at least a 0.13-micron process which won't be mature enough (at TSMC at least) until this fall to use for a mass production GPU.
From Anandtech's Parhelia-512 review.
ATi managed on 0.15 what 3D Labs thought wasn't possible. Not bad I say.
