ATI's next generation part codenamed R700 is scheduled for first quarter of 2008. ATI failed with every plan to make the R600 on market and still has to launch this part at some point in May.
We don’t know many details about R700 only that it will support DirectX 10.1 and Shader model 4. We know that the work in currently on the schedule and that this chip has to fight G100 chip from Nvidia.
We hope it wont be that late as R600 was, for DAAMIT sake.