Never Let Me Go
Here's the trailer: http://www.metacafe.com/watch/4778484/never_let_me_go_movie_trailer/
It's based on the book of the same name by Kazuo Ishiguro (author of The Remains of the Day). I read the book and it was quite good (although, without giving much away, is kinda depressing). I'm in the middle of Remains, and I've never seen the movie, though I've heard both are good.