Atlus has announced that Persona 4, the sequel to its well regarded RPG/turn-based combat/dating sim Persona 3, will hit North America for the Playstation 2 on Dec. 9. (Japan release is still July 10). The date comes at the end of the trailer above. If you have played the game and are familiar with the series, this should make sense to you. If you haven't, it won't. There's just no other way to put it.
I went to its wiki page (does that make me a hypocrite?), which says the game will be set in the countryside and the story involves a murder mystery. Weather replaces the moon as an event trigger. Also, no more shooting yourself in the head to get your magic on; the Evoker has been replaced by cards, which you destroy to unleash whoopass.
Persona 4 Web site [Atlus]