Nikon Japan has already listed the previosuly rumored Nikkor 800mm f/5.6 lens on their website. There is not much information except that the new lens will be on display during the The 141st Open Championship golf tournament (July 19-22, 2012) and Photokina (September 2012).
Update: I got the official press release, Nikon basically announced the development of the new lens, no further details were given:
TOKYO - Nikon Corporation will add the super-telephoto 800-mm, fixed local length lens to its lineup of NIKKOR lenses. This lens will offer a fixed focal length of 800 mm, a maximum aperture of f/5.6, and will be fully compatible with Nikon FX-format cameras.
This lens has been developed in order to strengthen the NIKKOR lineup of super-telephoto lenses. It will boast the longest focal length of any NIKKOR autofocus lens, and will be best suited to capture of a wide variety of decisive outdoor scenes, from sporting events to wildlife. In addition to its superior optical performance, the lens will offer dust and water resistance.
In 2012, Nikon released three new FX-format digital-SLR cameras—the D4, the new flagship digital SLR, and the D800 and D800E, which offer incredible resolution and image quality. In addition to reinforcing its lineup of FX-format digital-SLR cameras, Nikon has also been working to expand the lineup of NIKKOR lenses.
Nikon has been providing service and support to professional photographers for roughly fifty years through the activities of its Nikon Professional Services (NPS). In addition to providing maintenance and repairs for the equipment professional photographers use every day, NPS service depots are set up at a variety of international sporting and cultural events. At these service depots, photographers can have their equipment inspected and repaired, and they can also borrow equipment.
Nikon has been also an official sponsor of The Open Championship since 1993. The Open Championship is the oldest of the world's four major tournaments* in professional golf (the next Open Championship will be held at Royal Lytham & St. Annes Golf Club in Lancashire, England between July 19 and 22, 2012). This lens is scheduled to be on display at the Nikon service depot that will be set up for professional photographers working at the event.
Furthermore, this lens is scheduled to be on display at Photokina 2012, one of the world's largest photo and imaging exhibitions, to be held in Cologne, Germany from September 18–23, 2012.
*World's four major golf tournaments: Masters Tournament, U.S. Open Championship, The Open Championship, PGA Championship
As a leader in the professional imaging market, Nikon will continue to develop and release products offering superior performance and functionality based on the optical technologies it has cultivated over its long history. Nikon will also continue to strive to strengthen and improve the service and support it offers to its professional customers.
Release date and suggested retail price for this product have not yet been determined.
*Specification and equipment are subject to change without any notice or obligation on the part of manufacturer. Exterior finishing and design are not final.