The Hobbit: An Unexpected Journey will debut in theaters December 14, 2012 and followed a year later by The Hobbit: There and Back Again, in theaters December 13th, 2013.
Also, since the last post on the Hobbit (which you can read here) Hugo Weaving and Orlando Bloom have both signed on to reprise their roles as the characters they played in the Lord of the Rings trilogy, Elrond and Legolas, respectively.
According to the press release on the official The Hobbit website both movies are being filmed back-to-back and will be in 3D upon release. I put my faith in Peter Jackson that he will do 3D the right way, as James Cameron did with Avatar, and film the movie with the proper 3D equipment from the start.
Read the entire press-release here.