anand got some info up on the upcoming nforce board that will support sli (apparently not to be called nforce4)
http://www.anandtech.com/cpuchipsets/showdoc.aspx?i=2175
http://www.anandtech.com/cpuchipsets/showdoc.aspx?i=2175
Finally, the SLI version of CK8-04 ties everything together with an additional switching PEG solution. Even though the CK8-04 only supports 20 PCIe lanes, NVIDIA's elegant graphic solution runs 16 lanes into what appears to be a separate switching bridge chip. This bridge can be electrically configured to either run all 16 lanes to one PEG interface, or 8 lanes to two PEG interfaces. Remember, PCIe supports 250MBps per lane, so as long as the video card can electrically support itself on 8 lanes, the theoretical 2GBps (full duplex) per video card of a dual x8 configuration is more than enough for upcoming video card solutions for many revisions to come. Current 8X AGP solutions run at 2.1GBps (half duplex) video bandwidth without coming in reach of taxing out the bus.