Some quotes from the latest Kepler report (Nvidia's 600 series cards):
"First and foremost, in NVIDIA's internal nomenclature, this part should be named GeForce GTX 660 (the company is debating GeForce GTX 660, 670 or 680 - and the final verdict will 99% be GTX 680). This is a 349-399 dollar part which in conventional way would replace the 300-dollar "GeForce GTX 560 Ti 2GB", but will offer higher performance than GTX 580. Significantly higher… and more importantly, not just beating the $449 Radeon HD 7950 3GB, but also endangering the $549 Radeon HD 7970. Yeah, it is that fast."
"You won't need to wait for too long, as NVIDIA is already starting pre-sale activities, and getting ready to counter AMD and their momentum with the Radeon 7700 (Cape Verde, February 15), 7800 (Pitcairn, March 6) and 7900 Series (released)."
http://www.brightsideofnews.com/news/2012/2/10/real-nvidia-kepler2c-gk1042c-geforce-gtx-670680-specs-leak-out.aspx