ckmlb, many games that are denined multi-port eventually do become multi-port.
Enchant Arms is a quick JRPG title I can think of that had the lovely "only on Xbox 360" logo which proved false.
I'm not saying that FFXIII is coming to 360. But I do believe, provided certain circumstances (as I said, poor sales), might force SE to port the game. Expecially if RE5, DMC4, or any other Japaneese 360 multi-port did suprisingly well.
Back from the dead, I'm afraid.