The G92 is supposedly a new 65nm mainstream chip with a 256-bit memory interface that should compete against the ATI RV670. The G92 will have PCI Express 2.0 support, 5GT/s texture fill rate, Pure Video Gen 3, HDMI and display port support. The name of the G92 chip isn't know yet - but it will be part of the GeForce 8000 family.
NVIDIA is also working on the G98, a low-end chip that will compete against the ATI RV620.