It looks like NVIDIA are fans of the upcoming dual-GPU from AMD, the Radeon HD 6990. NVIDIA were approached at CeBit and were asked to pose in front of a camera with the Radeon HD 6990, which they agreed to, pearly whites included.

As the picture above shows, NVIDIA are in good spirits. This could mean a few things. They could be just smiling to get it out of the way, smiling because they know their product is better, or smiling in defeat. My guess is the NVIDIA's dual-GPU will be faster but at the use of much more power (400W+) where the HD 6990 should sit pretty at 300W and below.

This is just guess work, I'm the messenger, please don't shoot me.