The Hobbit doesn't have appendices. Lord of the Rings does. But from what I understand, a lot of the extra material (e.g. The White Council) comes from Unfinished Tales. I'll love seeing that.
Edit: I am a bit concerned about this becoming a trilogy... Part of me loves the extra material we'll get to see, another part knows how little was actually going on in The Hobbit. I don't want it to become like butter spread over too much bread (or however Bilbo puts it).
Part 3 will be awesome, with a huge dragon and the Battle of Five Armies. But what will part 1 and 2 have? Some stone Trolls, Beorn the shapeshifter, some (talking?) Wargs and Spiders, some Goblins... and Gollum. Even with the White Council stuff added, I don't know if it will entertain enough.
By the way, I read on TheOneRing that a 2 new domains have been registered. The titles of movie 2 and 3? That would make:
An Unexpected Journey
The Riddles in the Dark
Desolation of Smaug
Personally I'd have removed 'The' from title 2 and use it in title 3.
Edit2: Ah it really makes me want to read all my Tolkien books again.