We managed to find a few more details about G100. The new Nvidia chip will be a facelift of a G80 architecture but it won't be the same.
It will have the support for DirectX 10.1 and Shader model 4.1. The only other big difference compared to G80 generation is the new VP3 Video processor 3 that should take care of Video and HD content.
We still don’t know the technology behind the chip but we heavily suspect 65 chip.