Apple has just posted a beta version of CUDA software tools.

CUDA (Compute Unified Device Architecture) allows users to crunch mathematical formulas using the GPU resident inside a computer, speeding up otherwise lengthy tasks, such as encoding video or other rich media, as well as scientific and design uses. CUDA was developed by NVIDIA in 2006 as an architecture for advanced programming that takes advantage of additional capabilities offered by parallel processing with multiple cores. This compiler works by feeding calculation data to the massively multi-cored GPU systems, allowing them to break down the code in a shorter span of time than is normally required by sequentially-operating main processors.