It has been far too long since AMD/ATI have been at the top of the performance charts; the crown had been lost on both CPU and GPU fronts, but today's Radeon HD 3870 X2 introduction begins to change that. The Radeon HD 3870 X2 is the most elegant single-card, multi-GPU design we've seen to date and the performance is indeed higher than any single-card NVIDIA solution out today.
Link: ATI Radeon HD 3870 X2: 2 GPUs 1 Card, A Return to the High End