I could see how this may possibly be a hoax. I myself am now a skeptic as,
www.adventchildren.net is the only site reporting the news. I would think at least IGN would make an article about it.
And I haven't looked at Squenix's site yet, but I don't think they made a statement. Regardless the whole idea of this sounds feesable -- but I don't think it would be smart to make another game for the mobile platform. As another person said, they are wanting the compilation to hit a multitude of mediums:
AC: Movie/Cinema/DVD
BC: Mobile Cell Title
CC: PSP Title
DC: PS2 Title
EC: (another Mobile Title?) - Doesn't jive.
FC: (maybe Final Crisis? maybe PS3? maybe never?)