The one thing they don't say is how much power a GTX 480 actually consumes... if what Semiaccurate has been saying is correct, and they seem to have been right in their last articles, then the GTX 480 consumes so much power that they won't be able to build one using two chips, because that would largely exceed the 300w PCIe certification limit, which means the 5970 will have no competition.
Also, from what's being said - and shown, the GTX 480 will need a power supply with a single 12v rail giving 42A. You will clearly have to check you PSU carefully to see if it delivers those 42A over a single rail or something like 18A over two or three rails.