I'm willing to bet it'll end up as a multiplatform release. Given the state Square are reportedly in, they need every bit of income they can generate, and releasing Versus XIII on more than one platform will ensure they maximise the amount they can make. That may be why it's taking so long to release; having to develop the game for the 360 as well.
This is of course all speculation, who knows what's going to happen. I remember reading an article in which the lead developer said to look out for news soon, but I can't remember where I read it. Needless to say I can't wait for it, it's one of the reasons I bought my PS3 years ago.