The 12th Pokemon movie was screened at the Locarno International Film Festival. The movie was shown in Japanese with English subtitles. An English title was given to the movie: Arceus and the Jewel of Life. No official word yet whether or not this title is finalized. The Japanese title of the movie roughly translates into Arceus: To a Conquering Spacetime.
You can watch the Arceus and the Jewel of Life movie presentation and trailer from the film festival here: Locarno International Film Festival (then click on the Pokemon tab on the right of the video).
The movie was released in Japan on July 18, 2009. It will most likely be released in the US sometime in 2010.