I have seen The King's Speech and Black Swan. I loved both movies for different reasons. I have Inception at home and plan to see Winter's Bone and the Kids Are All Right, as well. I do like all these poster designs but the winner for me is Black Swan.
The photograph of Natalie Portman's face is so bold and compelling. It is a simple but powerful image. It really fits the movie which, is quite creepy.
My second choice is the King's Speech. I love the use of the orange and black and white photography. The lettering is simply done but elegant, as well. The movie was set just before WWII and I think the poster reflects the time of the movie.