ATI Radeon HD 5870 & 5970 with NVIDIA PhysX
If you haven’t heard already, the 257.15 Beta ForceWare driver set from NVIDIA accidently had the ability for ATI users to again use an NVIDIA card as a second to do PhysX. The whole ordeal created a bit of drama around the web; as soon as it was discovered by NVIDIA they yanked the driver and put another one up that disabled the ability.