The impressive fact isn't that it's 7 video cards, it's 13 gpu's.
It is still however extremely pricey, and is mostly a rippoff.
It's 6*GTX 295 (a GTX 295 hosts 2 GPU's) and 1*GTX 275(1 GPU)
6*2+1=13 GPU's
It's about the same as 6*5970(12gpu) + 1*5850(1gpu)=13gpu in ATI-world, which is about 4,5ghz, quite impressive but there are people on the forums with more ghz than that.