ATI makes dual GPU R600 - Radeon X2800XTX2@ 2007/02/15
"The top-of-the-line card will be known as the Radeon X2800XTX2 and will be the same concept as Nvidia's GX2 card. So you can expect two R600 chips on a card. We don't know how ATI plans to implement this, as we may be talking about two PCBs or maybe just one. Nvidia went for two PCBs last year with its Geforce 7950GX2 and our money is on ATI following a similar route.