Of course we all know it's on it's way, yet some info and photo's of the lower mainstream targeted Radeon HD 4670 popped up on the web. This videocard is based on the all new RV730 GPU , produced on 55nm and reportedly has 320 stream processors. What would pretty much boil down to the Radeon 3870 actually.
It is expected that this video card class will retail with 512 MB GDDR3 video memory. There's no info on clock speeds just yet.