Without getting into the nitty gritty details, NVIDIA provides boards to our developers for their in house game development. These boards are meant for the sole purpose of inhouse engineering and QA. In the case of the recent GeForce 7800 GS PCI Express reviews that you may have seen, some of these developer boards were mistakenly given out to end users at an event the developers sponsored. These boards were never meant to ship in the open market.
Since the 6800 GS is such an amazing card, it really sucks to not see a 7800 version. I guess it’s just too similar to the GT. Check out the posting at AnandTech.