Confirmed by Square-Enix's calender, on February the 17th the Kingdom Hearts II Ultimania booklet will be released, featuring exclusive detail on Kingdom Hearts II, going behind the scenes, visual art, (Not as much as the art booklet) the making of the game possibly. Rumored to show the 'origins' of the Organization. (What they did in their past time before they became nobodies) and much more plot, that was hidden in the game.
http://www.square-enix.com/jp/calendar/
http://www.square-enix.com/jp/calendar/