This chipset is for lower-end motherboards and is positioned under the nForce 650i SLI. The new nForce 650 Ultra supports the Core 2 Duo, Core 2 Quad and Core 2 Extreme processors and seems to have most of the features of the nForce 650i SLI.
The main difference is that this new chipset doesn't support SLI and should be a bit cheaper.