I think you'd be surprised if you looked at the full list of published titles.
Total Exclusives (Acording to Wikipedia):
Sony Published Exclusives: 65
MS Published Exclusives: 73
Here are the lists. I'm sure there are a few descrpencies or mistakes. But even if the 360 list had several mistakes it's pretty clear to me that the PS3 does not have a substantial advantage in published games.
Microsoft Published Exclusives:
Sony Published Exclusives: