http://www.apple.com/displays/digital.html - see bottom right corner:
Dual Link DVI
The 30-inch Cinema HD Display requires the next level of DVI connectivity dual link to drive the massive amount of pixels to the screen. And the NVIDIA GeForce 6800 Ultra DDL graphics card (available from the Apple Store) delivers, with the most advanced graphics engine available. This card, designed specifically to support the dual link DVI connection, delivers 2560 by 1600 resolution. And with two dual link connectors, it can drive two 30-inch Apple Cinema HD Displays, giving you the ultimate creative canvas. This card will be available for Mac only in August 2004.
Dual Link DVI
The 30-inch Cinema HD Display requires the next level of DVI connectivity dual link to drive the massive amount of pixels to the screen. And the NVIDIA GeForce 6800 Ultra DDL graphics card (available from the Apple Store) delivers, with the most advanced graphics engine available. This card, designed specifically to support the dual link DVI connection, delivers 2560 by 1600 resolution. And with two dual link connectors, it can drive two 30-inch Apple Cinema HD Displays, giving you the ultimate creative canvas. This card will be available for Mac only in August 2004.