According to the announcement aired on TV, Fullmetal Alchemist Movie will be premiered next summer. The title is "Fullmetal Alchemist: Milos no Seinaru Hoshi".

Screenshots of the trailer
FMA Movie official website (trailer on the lower left)

Staff
Director: Murata Kazuya (deputy director of "Code Geass: Hangyaku no Lelouch & R2")
Scenario: Shinpo Yuichi ("Doraemon: Nobita's New Great Adventure into the Underworld")
Character Designer & Animation Director: Konishi Ken-ichi ("Tokyo Godfathers", "Bokurano")
Production Studio: Bones

Story:
Edward and Alphonse are still on their journey being toyed by the fortune. Finally, a story about the forbidden <bond> will be revealed. (The automail on Ed's arm in the trailer indicates the movie is not a sequel to the second TV series.)

Source: Screenshot of the announcement

Updated on January 1st
According to the official website, the premiere date is July 2nd.

Source: official website