FUD Zilla has heard that AMD isn't working on a dual-GPU card based on the Radeon HD 4890 (RV790) GPU. The reason for this is power consumption, by putting two RV790 GPUs together you'd get as high as 380W in the worst-case scenario and that's almost 100W more than the TDP of a GeForce GTX 295.
The thermal design power for HD 4870 X2 was 286 Watt, while Geforce GTX 295 card powered with two GT200 55nm chips has TDP of 289W.
Pushing the new X2 to 380W would be a bit too much, but there is a chance that some of the partners will reach out and release such a card. Since AMD has quite a few overclocking partners on board, someone might consider doing it.