So Nvidia is on the top of the hill for now, that's great. Nvidia and AMD have fought to be the 'king' for a while now, slowly beating the competition until their the only ones left (Consumer sell point, I'm sure there's Companies that sell GPU's that I haven't heard of though.)
Nvidia had a time when they kept reusing the same architecture, and it brought them down; now it happens to be AMD's turn, but these are bringing the price down for the 5800+ series.
Really it's nothing surprising, I'm sure in 1-2 years AMD will come out with something that topples Nvidia's line up, and then Nvidia does the same. This is competition after all, we'll see what happens.