In an earlier post I made in pinoyxbox, it was pointed out that the infamous "Surfer Girl" blog (game industry rumormonger on the Internet) mentioned something about a "previously multiplatform action-adventure game series going Xbox 360 exclusive."
Today I found a post on NEOGAF which points out which game that might be:
2. ...or, they are announcing that the game is now Xbox 360 Exclusive?
In that case, we don't know yet what the answer is; unfortunately the one who posted the cover picture did NOT talk about the magazine's content, so I guess this is once again still a 'rumor' until more information is found.
In either case, this would be interesting if true---it would mean that Microsoft and Eidos are positioning this game to compete directly with the Playstation 3's equivalent game, "Uncharted: Drake's Fortune".