Official movie site is up:
http://www.hagaren-movie.net/
Teaser ran after Star Driver's airing.
Edit: Staff/cast credits added.
Original Work - Hiromi Arakawa
Director - Kazuya Murata
Script - Yuuichi Shinbo
Character Design/Chief Animation Director - Kenichi Konashi
Animation Production: BONES
The cast retains FMA:B's casting for the supporting characters as well as Ed/Al. Winry, Mustang, Hawkeye, and Armstrong are all confirmed characters. Story is completely original. Coming Summer 2011.
Edit2: I ripped some artwork from the official site too: