Sony is probably paying Konami lotsa buncha money to keep MGS4 exclusive.
Edit: apparently they don't:
http://www.eurogamer.net/article.php?article_id=78883
"We don't buy exclusivity. We don't fund development. We don't, for lack of a better term, bribe somebody to only do a game on our platform. We earn it by saying, 'You can build a better game on our platform. If you focus your development on our platform, you will ultimately be more successful."
Dorks.
