Nvidia has at least two unannounced chipsets listed in a new driver. You heard about NVIDIA MCP61 before and this one will end up being branded as the NVIDIA GeForce 7050 PV / NVIDIA nForce 630a.
More important is the inclusion of the Nforce for Intel, called MCP73. This chip was originally scheduled for Q1 2007 but it mysteriously slipped into Q2. With DAAMIT concentrating its efforts on the AMD market, Nvidia has a fighting chance to make Intel G965 and the upcoming G33 run for its money.
Nvidia has sixteen different SKUs based on this chipset, at least they are listed in one of the upcoming drivers.