FUD Zilla reports AMD has working R680 prototypes. These cards use two RV670 chips on a single PCB but the firm is still working on the driver support.
This is the card that will make quad Crossfire possible and theoretically with four of these cards in 790FX motherboard, you will be able to make even octo Crossfire but we are not aware of any plans for such a platformance or a driver.
AMD has already made the cards with two 2600PRO chips but no one dared to launch the product in retail, so making the card with two RV670PRO chips was not so difficult as people had some experience with two cores on a single PCB. The great thing is that a new R680 card consumes less power than dual 2600PRO card as its chips are 55nanometre.