Here is my "answer" to your question. You can buy the ATI cards now...unless you are willing to waite for 3-4 months for a price drop of any importance. The reason I say that is.
(a) fermi is going to be about the same price as the ATI parts.
(b) If Nvidia had something performance wise to brag about, we would have heard about it by now.
(c) The 470 and 480 are going to be in short supply
(d) The most important reason...assuming (c) is correct.....most of these cards will be bought by people who waited for them (read: Nvidia fans) and ATI knows that no price drop was going to get them to buy ATI.
The only 2 things that could change this are...much better performance by the Nvidia parts...probably not going to happen....or better supply of cards than expected.
But in gaming world there is the Physics part in the equation......?
Of cource this is all IMHO.......