Horror master Stephen King and production kingpin J.J. Abrams are in talks to bring King's masterpiece The Dark Tower to life, according to the Hollywood Reporter. Abrams has pre-approval for both film and television adaptations, though a project has not been started for either venue. The series spans seven long novels --- King has long lost sight of the "Backspace" key --- and weaves in dozens of major and minor plot threads, many of which lead to other books he wrote.
This would tends to suggest a miniseries, or even an actual television series might be in order to do the tale justice. However, considering the wide-scale themes of parts of the book, in which all of reality hangs in the balance, a big-screen adaptation might be the way to go. Fans of the series are already snapping up copies of the "Dark Tower" comic, an adaptation of parts of Dark Tower Book IV: Wizard and Glass as written by Peter David, so there is definitely a market for whatever eventually comes of this project.