Or 800/5.6G in FX terms...just in time for London 2012. Price TBD, although if you have to ask, you probably can't afford it. http://www.nikon.com/news/2012/0712_nikkor_01.htm
As expected, while it hasn't been released for the general public, their pre-production models are in London: http://www.leonneal.com/blog/2012/07/31/nikon-800mm-f5-6-preview/
The price is rumored to be $10,200. ; I'm surprised its that low since the SRP for the 600 f4 is $10,299. ; I guess it being an f5.6 makes a little bit of a difference.