I thought people here might be interested in the new CUDA 1.1 SDK, which includes some new physics demos including particle systems, FFT-based 2D fluids, and n-body gravitational simulation, all running on the GPU.
http://developer.nvidia.com/object/cuda.html
http://developer.download.nvidia.com/co ... ation.html
http://www.youtube.com/watch?v=RqduA7myZok
Enjoy!