ATI revealed stream computing this week and NVIDIA is also developing technologies to use GPU's computation power for other things than just graphics:
Nvidia, for its part, is also working on ways to use the GPU as a coprocessor, and in a conference call last week they reported that they're attacking similar problems but from a different angle. I tried to pin them down on exactly what they're working on, but I was unsuccessful. Even though all modern GPUs are technically a type of "stream processor," it seems that Nvidia doesn't want to push whatever they're working on as yet another stream processing-based initiative. Whatever it is that they're doing, it's supposed to make the GPU a better fit for general-purpose computation by adapting the GPU itself to different types of HPC problems.