AMD have chosen to make their CrossFire multi-GPU technology open for 3rd party motherboard chipset makers to be able to include it freely on any of their motherboards with dual PCIe x16 slots. They call it the "Open Multi-GPU Chipset Platform" initiative and it should allow for motherboards from NVIDIA, SiS and VIA to also start producing boards with the "CrossFire ready" logo on the packaging.

For more info, have a read of these articles at HKEPC and Tech Report.

Tech Report):-
Currently, only AMD and Intel 965/975-series chipsets support CrossFire multi-GPU configurations with ATI graphics cards. However, HKEPC says AMD is planning to further open CrossFire so that the technology can work with any motherboard that has dual PCI Express x16 slots. This so-called "Open Multi-GPU Chipset Platform" initiative could bring CrossFire support to motherboards with Nvidia, SiS, and VIA chipsets.