Unfortunately, as of June 2012, there are no reported plans to make Eldest, sequel to Eragon, into a film.
Eldest is the second novel in the four-book fantasy series the Inheritance Cycle by Christopher Paolini, which focuses on a boy named Eragon and his dragon, Saphira. Eldest follows after Eragon, which was made into a film in 2006.
Why Aren't They Making a Film?
Before the film Eragon came out, author Christopher Paolini was asked about the possibility of making a film adaptation of Eldest, and replied “I think we’ll know after opening weekend,” suggesting that they would only make another film if the first was well-received.
Many fans of the novel were disappointed with the film Eragon as it strayed from the book, and it wasn’t very popular with those unfamiliar with the Inheritance Cycle series either. It was criticised for being lifeless and for lacking depth and energy. Trusted film review website Rotten Tomatoes gave the film a rating of only 16% - that's the equivalent of one and a half stars out of ten!
As a result of this largely negative reception of Eragon the movie, it doesn’t seem likely that Eldest will be made into a film any time soon. Personally, I think it's more likely that they'll reboot the film series entirely (as has recently happened with Spider-Man) than make a sequel to the Eragon film.