After a long delay, ATI finally released their CrossFire technology, that allows to use, as well as NVidia's SLI, the cumulate power of two PCI Express video cards.
Hardware.fr en a publié un test.
This technology seems to be reliable and functional, even it will request a specific motherboard with two PCI Express ports (and a compatible chipset) to exploit it.
It is to be hoped that Apple shall implement in their future top of the line MacIntel two PCI-Express slots.
This is all the more possible that Intel is reportedly preparing a chipset that will be able to use both NVidia's SLI and ATI's CrossFire.
Beside the gaming aspect, coupling two high end video cards would deliver Core Image a tremendous power : a good way to seduce video professionnals.