Remember that drivers make a huge difference.
Those results will be a little off since the GTX 480 will be on RC/Beta drivers and the HD 5870 will most likely be on 10.2's giving it a decent FPS boost after the drivers have matured.
If you look at it that way, the GTX 480 will only get quicker. So a positive outlook for nVidia, until the price is seen, then it isn't so good.