If this turns out to be a good game, then I hope it does go to PS3, for the same reasons I hope MGS4 comes to 360, people should get to enjoy games regardless of their console choice.
Then you think Final Fantasy XIII and Versus XIII should go to the 360 as well?
I seriously don't like that idea at all. If you cancel out 3rd party exclusives it changes the entire gaming market and for the worse. All games then don't get the time required to fully utilise the consoles capabilities. Even if the 360 gets MGS4, it will not be the same experience that the PS3 version offers because specific games are bulit using a specific hardware and ports simply don't get the time put into them.