HardOCP has some information about NVIDIA's graphics card plans for the first half of the year. As it looks right now, it seems that we shouldn't expect any real next-generation cards at least until mid-2008.:
GeForce 8800 Ultra will be replaced by the GeForce 9800 GX2 in February / March timeframe.
The GeForce 8800 GTX will be replaced by the GeForce 9800 GTX in February / March timeframe. This card will support Tri-SLI.
The GeForce 9800 GT should appear in the March / April timeframe. We have limited information on this card currently.
The recently “released” GeForce 8800 GS will be a limited GPU in terms of production. Do not expect more than 100,000 GPUs to be shipped worldwide, but soon. ASUS will supply Asia, Palit will supply China, EVGA will supply North America, and XFX will supply Europe. The GS is an “inventory solution.” The 8800 GS is 192-bit bus and will ship in 320MB, 512MB, and 640MB versions with a trimmed down number of stream processors as well. Will fall in line below 8800 GT but above the 9600 GT.
The GeForce 9600 GT will fall in line below the 8800 GT, but give better performance than the GeForce 8600 GTS. The 9600 GT will be a whole new card not based on the 8800 GT PCB. Price point should be at $169 in retail/etail and plans are to carry this GPU throughout 2008.