Although to be taken with a few grains of salt, there's been some test results of NVIDIA's upcoming dual-GPU based GTX 295 graphics card posted over at it168, which since seems to have been pulled. However, Techpowerup were able to get hold of some of the results beforehand as well as an image showing the the complete cooling assembly for the card.
You can see the rest of the results here. There are instances where as much as 80% gains can be seen over the HD 4870 X2 and the results show that the card uses less power as well. But be aware that these are far from conclusive at this early stage and it will be a month or so before concrete details on performance and pricing begin to surface.