A small but very important piece of information concerning NVIDIA's GT300 series GPU's just surfaced.

The new series from NVIDIA will feature no less than 512 processing cores that will be arranged at 16 32-core clusters. Furthermore, these cores will be MIMDs (Multiple-Instruction, Multiple Data), not the SIMDs (Single-Instruction, Multiple Data) that NVIDIA currently uses.

This should make for a healthy performance increase coupled with support for DX11, OpenGL 3.1, and OpenCL. Clock speeds aren't mentioned but you can probably count on an increase in at least memory speed if not other areas as well.