NVIDIA and ATI Show Working PCIe 2.0 GPUs
"That was a move that took me, personally, by complete surprise. Neither set of cards were identified, but they both were running two cards on 5Gbps links.
It was only about a month ago that NV showed off their chips behind closed doors at the PCIe SIG meeting. ATI wasn't there. Now, they are both here, and both are working."