GTX 295 is the best Nvidia does, but has a bad price/performance ratio....read the article on front page of anandtech.com, you can't beat a Radeon 4890 as far as how much performance you get per dollar. If you really want to go super high end then get a 4870 X2 or crossfire 2 X 4890's.
I could never spend +$500 on a video card like GTX 295 when I know there are much cheaper alternatives that still get you great performance.
New video cards from Nvidia and AMD/ATI should be out by end of Q3 this year, or at least we should see benchmarks by then.