[DoomUK]

Can't see this posted anywhere here yet, so for the benefit of anyone who hasn't heaerd about this:-

http://www.havok.com/content/blogcategory/3/53/

Havok announces plans to support GPU-accelerated physics through Havok FX™. This new product from Havok will utilize the native power of Shader Model 3 class graphics cards, like the NVIDIA GeForce 7800, to deliver physics effects that integrate seamlessly with Havok’s industry-leading game-play physics technology found in Havok Complete™. Havok FX will be cross-platform and will take advantage of current and next-generation GPU technology to deliver eye-popping effects that visually enhance the gaming experience. Havok FX will allow developers to leverage the growing installed base of cutting edge graphics cards and their powerful, standardized APIs - to offload floating-point operations that are necessary for simulating a broad-range of dynamic visual effects.

Sounds like a logical thing to do to me, although it'll probably work out that a dedicated PPU (i.e a PCI expansion card or otherwise) will provide better support/functions than an intergrated solution, i.e GPU-accelerated physics. It's much like how CPU architecture can render graphics, although with very limited functions compared to a dedicated GPU.