Found this article on KHInsider.com:
Working on unannounced game?
The Forums on KH Insider do have some ideas as to what it might be, but their guess is as good as mine. I doubt it's anything Kingdom Hearts or Final Fantasy because they already have a lot of those games either already out this year or will be out this year. It's probably a "stand alone" type game that most people will ignore unless it's exceptional.
The World Ends with You 2 would be interesting though. I'd like that.