Whe I said Persona Q was Atlus' oddball announcement of the night, I was lying. Persona 4: Dancing All Night definitely takes the cakes as oddity of the evening. Yes, Dancing All Night is exactly what it sounds like, a rhythm game starring several Persona 4 characters including Rise Kujikawa, Yu Narukami and others. Expect Persona-grade wild story mixed with, well, lots of dancing exclusive to PS Vita and releasing fall of 2014 in Japan.
The project is being co-developed between Atlus and Dingo Inc, who you may recognize as the team behind the Hatsune Miku: Project DIVA titles. I'm... not really sure what else to say. It's a Persona 4 rhythm game. Here, let me offer up a quote from the announcement trailer that properly captures my mindset: "Can you imagine the step? It's genius!"
Persona 4: Dancing All Night will is a PS Vita exclusive that is planned for release in the fall of 2014 in Japan. This one sounds rather niche, but judging by Atlus' dedication to localizing most of their bigger releases recently, I'd say a localaztion in the months after Japan's release is certainly possible. I'm sure there'd be a lot of disappointed Persona fans if they didn't get this game. Well, they'll always have Persona 5 and Persona Q.
Thanks to @Rabla for the heads up!