The only problem is Hideo said it will be using the whole disc, and may need a second one. To say it has a high chance of 360 would be stupid.
Snake alone has the most free movements I've seen in a game. Being able to crawl, roll, and roll onto his back and shoot are just a few things that separate this game from any others. Even now 360 cant do half as much. The biggest game Mass Effect will be a basic shooter. Like Gears was a detailed game, but not much as far as character freedom.