As most of you know, the GeForce 9800 GTX is based on the G92 GPU which is the same as used on the 8800 GT 512 MB and 8800 GTS. Even though NVIDIA calls this "GeForce 9" I don't really see much progress compared to "GeForce 8".
Of course you will have the GeForce 9 bragging rights when choosing this product, which offers almost only slightly better performance compared to the GeForce 8 products.
If you are an SLI fanatic, this card can also be used in triple SLI, which the GeForce 8 cards can't. Another unique feature is the support for HybridPower which completely shuts off your graphics card and renders on the integrated NVIDIA graphics of your motherboard (if you have such a motheboard). This helps to save a considerable amount of power.