Although you'll be hard pressed to get an answer as to what it actually is, Square Enix has hinted at a new game project in a fairly nondescript trailer bundled with the Japanese version of Dragon Quest VIII, which is currently doing the retail dance in the Far East.
Called "Code Age", whatever it is, Square Enix considers it a "new concept brand" and doesn't specify any platforms or specific games, leading to speculation that it will be exploited across multiple forms of media - much as the company's been doing recently with Final Fantasy VII. The fact that Square Enix already owns a number of US trademarks derived from Code Age seems to support this.
What we do know is that Code Age seems to use cel-shaded visuals, and will be directed by Yusuke Naora, whose work spans Chrono Trigger, The Bouncer, and various Final Fantasy projects including VII, X and Advent Children. Naora was also a character designer for Unlimited Saga.