Leaked: Nvidia GeForce GTX 580 specs and images

A rough and dirty calculation would say that it's 7% increase in shader count multiplied by a 10% increase in clockspeed = 17% performance gain (not accurate to any great degree but a reasonable starting point.)
TDP is rumoured (supposedly corroborated by an MSI employee posting at B3D) to be ~230w -actual as opposed to the 250w of the GTX 480 which in actuality can reach 280 in gaming and 300+ under Furmark so around 22% improvement in maximum board power (GPU+ VRAM). A little math then says 117% of the GTX 480's performance divided by 78% of the GTX 480's TDP = 50% improvement in Performance/watt. No too shabby if true, and a huge improvement for a card whose only real failings were power consumption and the associated noise/heat output.
I would have preferred the card be called the GTX 485 or 490 if the chip design is a respun GF100 for low-leakage

EDIT
I guess we'll know soon enough, Asus have their GTX 580 already listed...although at $599 it's not for the budget minded. November 9th supposed launch day- hopefully the cards hit retail before Christmas.
Hopefully TS have their review sample close at hand.