Carried this one over since it happened so late. John Carmack has a .plan update in response to a lot of people asking him to comment on the new "NVidia card with the funny name" and the Apple G4. Here is his take ont he GeForce256, and you can read the whole .plan at fingershack.com for what he thinks of the G4

Nvidia's new geometry accelerated card with the funny name.
It is fast. Very, very fast. It has the highest fill rate of any card we have ever tested, has improved image quality over TNT2, and it gives timedemo scores 40% faster than the next closest score with extremely raw beta drivers. The throughput will definately improve even more as their drivers mature.For max framerates in OpenGL games, this card is going to be very hard to beat. Q3's target of about 10,000 triangles a frame doesn't stress this card at all. If you want more polygons out of Q3, you can do:

r_lodBias -2 // don't use lower detail models
r_subdivisions 1 // lots more triangles in curves
r_lodCurveError 10000 // don't drop curve rows for a long time