http://www.anandtech.com/video/showdoc.aspx?i=2769This time around NVIDIA's flavor of SLI and PCIe are being used to connect two boards together for a full featured multi-GPU solution that works like a single card as far as the end user is concerned. No special motherboard is required, the upcoming 90 series driver will support the card, and there is future potential for DIY quad SLI.
They have it benchmarked at a 28-46% (config dependent) performance increase over a 7900GTX in FEAR. It beats out a 7900GT SLI config on almost everything too.