AMD is preparing a design kit for dual RV670 card and as dual RV630 cards are real, so is the dual RV670.
The story is quite simple as dual RV670 will draw even less power at least theoretically due to to its 55 nanometre design and such a card is possible and very likely. If the story of Quad Crossfire becomes a success ATI will have sub $500 card to fight Nvidia’s Geforce 8800 Ultra or Geforce 8950 how Nvidia likes to call its G92.
After dual RV670 comes R700 and that is ATI’s real high end. The question remains what Nvidia has versus G100..