Persona 3 is getting an official anime movie adaptation in 2013, and from the looks of it more will follow. The official site teases "Movie #1" in 2013, which implies that we can at least expect a second to come some time afterward.
The film's official site (via Siliconera) is sparse, but fans have already started speculating on what the other movies could mean. The story of Persona 3 is dense, and didn't have its own animated series like Persona 4, so it could be split into multiple films. Alternately, it could be offering similar movies with separate protagonists, similar to how P3 Portable had a selectable female hero.
This movie is planned for Japan, obviously, but Persona 4: The Animation is set to be released in North America early next year. A Persona 3 film would likely get a similar treatment.