In a Facebook post entitled "An unexpected journey", director, producer, and writer Peter Jackson made a surprise announcement: "that two [The Hobbit] films will become three." Apparently, he recently sat down with co-writers Fran Walsh and Philippa Boyens to watch an early cut of the first movie and a "large chunk" of the second, only to realize there was so much more of the tale they could tell.
We know how much of the story of Bilbo Baggins, the Wizard Gandalf, the Dwarves of Erebor, the rise of the Necromancer, and the Battle of Dol Guldur will remain untold if we do not take this chance. The richness of the story of The Hobbit, as well as some of the related material in the appendices of The Lord of the Rings, allows us to tell the full story of the adventures of Bilbo Baggins and the part he played in the sometimes dangerous, but at all times exciting, history of Middle-earth.
Not counting the aforementioned appendices in The Lord of the Rings, The Hobbit is roughly 300 pages. That may not seem like a lot to those that haven't read it, but there is certainly a lot of material contained within those pages. Peter Jackson successfully brought The Lord of the Rings trilogy to the big screen, so here's hoping he brings that same magic to The Hobbit films. No word on the release date of the third film, but the first two are scheduled for December 14, 2012 and December 13, 2013, so I would expect the third one on December 12, 2014.