ChainsawAsh said:

I'd be really annoyed if it turns out to be bookended by Elijah-Frodo reading the story from Bilbo's book...

Why? It makes perfect sense from a marketing standpoint. From what I've read, there are only a couple of characters from the LOTR stories in The Hobbit. If they're going to get people other than the LOTR fanbois into the theaters, they have to feature some of the characters from the LOTR films in some capacity. Since Frodo doesn't appear in The Hobbit at all, using him as a framing device in the film makes sense, and adds the recognition factor they'll need to help make an otherwise unfamiliar story a success. (Besides, they have to do something to pad out a single book into two films...)