Source: The Inquirer
Nvidia PCI Express stuff was scheduled for Q4 and it hasn't changed from that so far. We wrote Nvidias C8K-04 captured in living hues and now we know that this is the Nforce 4 project. µ
Last time we asked Nvidia's Drew Henry director of this chipset business about Nforce 5 for Intel CPU's he said laughing where is Nforce 4. This is your answer Drew.
NVIDIA Nforce 4, PCI Express for the AMD K8s

The name of NVIDIA's chipset that will bring PCI Express to the Athlon K8 market will be NFORCE 4. The NFORCE 4 will be socket 754/939 and 940 compatible and all Athlon 64s, FX, Opterons and Semprons will work on it. This chipset only features one PCI Express 16 slot, so the new GeForce 6800 SLI mode isn't possible on desktop boards based on this chip.