ATi is preparing its R420 AGP for Q2 this year, probably soon before, on or after the CeBit exhibition. Just like NVIDIA's NV40 it supports DirectX 9.0c and Shaders 3.0.
Cards will use GDDR 2 memory 256MB at 256 bits. It's possible to use 128 implementations as well. This chip be able to support DDR, DDR2 and GDDR3 so whenever it's ready ATI can make it work with its current memory controller. They will of course use 8x32MB chips.
The chip itself will be produced using a 0.13µ process and we are quite certain that it will use its heavily marketised low k process as before.