Not many details are out for either. Other than NVIDIA will have a 16 pipe design, use GDDR3 memory, and the PCI-express parts will be bridged from agp, meaning they arent going to be true PCI-E.
ATis boat is very similar, although they claim true PCI-E support, are going with the same 8 pipe design they have from the R3XX, and will use GDDR3 memory on high end boards with regular DDR at the low end.
Both are rumored to fully support PS/VS 3.0 (not that it matters in any way shape or form), which is a major part of the DX9.0c specification.
Again some of this is rumor and we could be getting some flamethrower POS parts cooled by holy water or something
