Metal Gear Solid Rising - Not Exclusive To The XBOX 360.

Why? Because it's not exclusive.
[quote]
"You know, we didn't say that it was exclusive," clarified Xbox executive and corporate VP John Schappert (he was the guy hosting most of the event) during an interview with me immediately following the press conference.

"We said that the next Metal Gear will be coming [to Xbox 360]," he said.

"I couldn't be more excited about him [Kojima] working on that [Metal Gear Solid Rising] and having that be part of our show," said Schappert. "When I heard about that, I was pretty ecstatic and it was an honor to be able to be on stage with him and announcing his next Metal Gear, which will be on Xbox 360."</blockquote>

It's pretty much certain that Kojima will be at Sony's press conference tomorrow.