The Australian PSM had an interview with Square-Enix's Motomu Toriyama. It was all right. He mostly talked about the main Final Fantasy XIII game. But he was asked a question that wasn't expected and he gave an answer that was even less expected.
What was asked? Dunno. What was said? "In fact, the Fabula Nova Crystallis Final Fantasy XIII project isn't just limited to three titles -- there are many different aspects. In terms of the formats we're reaching, as well, it's not simply exclusive to the PS3 and mobile phones. There is more."
Now, before all the competing consoles do a jig and cry in happiness for a game they wouldn't even play, this doesn't say anything about the exclusivity of XIII and Versus XIII. What we're gleaning from this is another game for another platform -- maybe Crystal Chronicles on the Wii actually takes place in the same universe? Or an Advent Children-style short movie where the two main characters of the games meet and duke it out? It's pretty interesting to think about -- oh, a graphic novel! Maybe.