I translated some of the official Persona OA webpage and posted it on Tumblr.
You can read my full summary here:
http://take-your-heart.tumblr.com/post/170958006331/more-persona-oa-info
But for TL:DR people: It will be the official “persona†series integrated mobile app. It will include:
The latest information on the series
An exploration game (It includes using personas, not much else is known yet)
Conversation events (so socials link, but these will be all new stuff exclusive to the app)
Persona Points to save and use (used for leveling personas, getting web content, for gifts, and for entering events)
A functional calendar with the ability to set up notifications
The app will be completely free and will be supported on iPhone 5S or later Android 5.0 or later. Pre-registration is going on now, and people in Japan who pre-register get to enter a lottery for IRL prizes.
Personally, I'm stoked. I'm not a big fan of rhythm games like DSN/DMN, but this is right up my alley. I'm begging for this to get an English version, my Japanese isn't nearly good enough to play the full game in Japanese. I still pre-registered and am still going to try to play it, though.