All you need to do within the BIOS for CrossFire or SLI is enable Peer to Peer writes provided the chipset has the proper amount of PCIe lanes available, there are a couple of other minor BIOS tweaks but that is the major one. The drivers will then determine if the board will run CF or SLI.
The ATI CF drivers are basically open and will enable CF operation if Peer to Peer Writes are enabled and the card support is in the code. That is why you see CF on the NVIDIA 680i SLI boards in the HP Blackbird as an example. ASUS did a simple BIOS code flip on their Striker Extreme board for HP, the retail 7.9 drivers work just fine as will future drivers from ATI, err, AMD.
NVIDIA performs specific chipset ID checks (these checks are hidden in a maze of black box type coding) in their drivers which is why SLI is only, officially, available on their boards. We had SLI working on the 975X almost two years ago, had it working earlier this summer with the 158 drivers (8800 Ultras) on the X38 also. However, NV is not going to make it easy for the manufacturers or Intel to license SLI support for the X38 or future dual+ x16 capable chipsets. At this time, do not expect SLI support on the X38 boards.
I personally think it is all BS, let the market determine the best chipsets or GPUs to utilize in a dual, tri, or quad GPU configuration. If it means an Intel chipset with a NVIDIA GPU or a NVIDIA chipset with an AMD GPU, so be it, but let's quit pretending this technology is limited to a particular vendor's component design.