As it stands...

NVIDIA's 500 series GPUs have only seen one release, the GTX 580 in early November.  As noted in my review of the GTX 580 at nV News, I am pleasantly surprised by the increase in efficiency and reduced heat output vs. the GF100-based cards.

Well, more 500 series GPUs are coming, and soon.  There is a ninja editor at Wikipedia who has been pretty darn accurate over the last 9 months or so regarding specs of upcoming GPUs.  Here's the updated 500 series chart as of 11/27/2010:

If this chart is correct, it looks like the Geforce GTX 570 will line up-performance-wise about equal with the GTX 480, and the GTX 560 will perform like a GTX 470.  This kind of performance coupled with the lower TDP of the 500 series should prove to be a very competitive effort on NVIDIA's part in Q4 2010/Q1/2011.  But wht of AMD's upcoming HD 6950/6970/6990?  Time will tell, and I'll report on that later.