I found this comprehensive list of upcoming King movie/tv projects at studiosystemnews.com:
The Overlook Hotel - Glen Mazzara is adapting this.
The Ten O'Clock People - Already cast and seeking funding.
The Long Walk - Frank Darabont to direct.
The Stand - Scott Cooper to direct.
Joyland - Tate Taylor to direct.
11/22/63 - Produced by JJ Abrams. Probably for TV.
IT - Directed by Cary Fukunaga.
Cell - Directed by Tod "Kip" Williams, starring John Cusack.
The Dark Tower - Directed by Ron Howard, starring Russell Crowe.
The Breathing Method - Produced by Jason Blum.
Pet Sematary - By Paramount Pictures.
Firestarter - Remake by Universal.
Children of the Corn - Dimension Films, directed by Darren Lynn Bousman.
Get all the details of each project HERE. Don't forget that these are not set in stone and some may never move forward into production.