NV30 has been done for many many months. they had working versions in Feb. for all we know, NV35 has taped out or will shortly. NV30 isn't cutting edge to Nvidia anymore, even though it's just being introduced to the public. I'm not saying NV35 will be out in March, but June-July isn't out of the question. or shouldn't be out of the question. And I don't think NV35 will be any massive improvement over NV30. it'll likely be the same overall architecture, but somewhat enhanced with more vertex math engines, new AA unit, maybe a 256-bit bus. I'd expect the additional vertex engines since NV30 has equivalent of LESS than the 4 vertex shaders that R300 has. R300 can do 1M polys per Mhz. or 1 poly per clock tick. (i believe that's correct) only way NV30 pumps out more polys is because it's clocked so much higher.
NV35 should have the usual faster core clockspeed with more memory & faster memory. sounds like a lot because i went into detail but what i described isnt that different from NV30. no more different than NV25 is over NV20. the NV35 should have the same vertex and pixel shader instructions as NV30, so no major change except for the AA method (hopefully!), just mostly higher performance. Nvidia probably won't even annouce it til May, 6 months from now. Otherwise, Nvidia is looking serious behind schedual if all they have in the spring is a slightly faster NV30 or nothing new at all.
just my speculation....