Shutter Island - This new Scorsese film is such a mind bender that it'll challenge you to think throughout the movie just to keep up. Set in the 50's, Leonardo DiCaprio plays a U.S. Marshall sent to an island of crazies to investigate a missing patient. DiCaprio has proven what an excellent actor he's become, plus there are great performances by Ben Kingsley and Michelle Williams.
It reminded me of some of the old Hitchcock psychological thrillers like North by Northwest or Vertigo. Although it's not my fave Scorsese film (that's either Good Fellas or Taxi Driver), it's definitely in the top 5.