The Hollywood Reporter has now confirmed that Sam Raimi has, indeed, boarded MGM's upcoming remake of Poltergeist, but is doing so in a producer-only capacity alongide Nathan Kahane and Roy Lee.
Raimi, who directed The Evil Dead one year before the first Poltergeist was released, is also known today for, among many other films, his Spider-Man trilogy and, most recently, for Drag Me to Hell. He's currently in post-production on Oz the Great and Powerful.
No director is currently attached to Poltergeist.
Will keep you posted.