Exorcist: The Beginning: Thanks to our friends over at Latino Review, we've got a description of what to expect from the trailer for the upcoming Exorcist prequel:

"Starts with the voice over of Father Damien asking Regan all the questions he asked from the first film, "who am I talking to, how old are you," in which Regan replies "12" and then all of a sudden you see Regan's ugly possessed face on the screen, and it then turns black and you see images of the first film going backwards, you see Father Damien who jumped out the window and fell on the stairs fly backwards up to the window and into Regan's room, and you see Father Merrin go backwards into the taxi in front of Regan's house and [which is shown on the Exorcist poster] quickly the screen turns black. Then the words "GO BACK, GO BACK, GO BACK, GO BACK .....TO THE BEGINNING" appear on the screen. You then see the young boy who is now possessed by the devil, and all sorts of action starts popping up, like the young priest played by Gabriel Mann in a tomb flying in the air dropping his rosary, and it ends with the theme song from the first Exorcist. The trailer is pretty cool and scary especially when the boy rises from his bed with the white pale face."
Brian B.