DDR3 supporting Nforce 790i will launch on March 11th. This looks to be a simultaneous launch to follow the launch of 9800GX2, but Nvidia has pushed this launch already a few times.
This is basically a fixed 680i chipset that can support Quad-core 45nm Penryn and DDR3 memory. This chipset supports tri-SLI and it can support FSB 1600. There will also be a Nforce 790i Ultra.