We talked to some boutique PC vendors whose job is to sell very expensive, ultra high-end PCs, and they confirmed that most of their customers are still waiting to see the Geforce 9800 GX2.
Many customers have asked for two Radeon 3870 X2s as an alternative, but so far most have abstained from buying them. They want to see the numbers of Geforce 9800 GX2 times two before they make this expensive decision.
They simply believe that ATI still has to win its 'face' back in the ultra high end market, and this might be a tough task, as Nvidia won the last few years in a row.
There is no doubt that ATI has been better than in the last three+ years, but at the same time, it takes time to re-win your face and pride back.
If Nvidia fails to scale well with two 9800GX2 cards in Quad SLI, they will be in deep trouble.