No, it isn't coming this year. Nvidia hasn't shown any dies [AMD did this for Evergreen 4 months prior to its release], has been talking down DX11 (when they did that with DX10.1 it was a year before any NV DX10.1 parts appeared) and no information has been leaked on it except by known false sources (who gave incorrect Cypress specs).
The only reporting I've seen on this is that i) Nvidia's internal roadmap shows it coming next year, ii) it taped out early August and yields are sub-10% so they couldn't possibly launch it and iii) if they were launching it then why would they launch 40nm GT200 parts in 3 weeks? It will take 3 months to respin GT300 so the yields are up, and then another 2 months to get boards running and production volume up. That puts it in February, that's my best guess.
The source for i) and ii) correctly leaked Cypress's shader count (1600) and Cypress's performance being around that of a GTX295. His leaks on GT300 are that it has a die size of ~530mm^2, an NVIO chip and four variants for different market segments.
Even then, unless they revolutionise GT200's IPC then given the 40nm scaling and the die size they would have a chip marginally faster than the GTX295 and 5870. But it would be so large (no one's ever attempted a card with that much silicon area, even the GTX295 lost tons of money when it first launched) that it couldn't have an X2 version so would lose to the 5870 X2.
