We're not sure what to believe anymore as some sites contradict each other but according to DailyTech NVIDIA is definitely working on a faster GeForce 8800 GT graphics card with more shader processors:
According to company guidance, the new G92 will launch in early December and feature 128 shader units as opposed to the 112 featured on GeForce 8800 GT.
This would be mean the additional 16 shader units exist on all GeForce 8800 GT cards, but are disabled for yield or marketing purposes. In addition to the extra shaders, the new G92 will also feature higher core frequencies and support for up to 1GB GDDR3.
The new 65nm G92 has a tentative SKU designation of GeForce 8800 GTS. This might sound confusing as NVIDIA already sports a GeForce 8800 GTS card based on the 90nm G80 silicon. However, since G92 sports a 256-bit memory interface, the new 8800 GTS cards will feature traditional memory blocks of 512MB or 1024MB. The older, G80-based GeForce 8800 GTS features 320-bit memory blocks of 320MB or 640MB.
As the new GeForce 8800 GT generally outpaces the existing GeForce 8800 GTS, the new GeForce 8800 GTS will likely surpass NVIDIA's high-end GeForce 8800 GTX and potentially GeForce 8800 Ultra.