The App Store is a lucrative business. Not just for Apple, though. For the thousands of developers who host apps in the digital storefront, it can mean big earnings, too. If anything, it's just a way to get your name, company, app, or game out there in front of a lot of eyeballs. So of course Microsoft would very much want to make sure it's accessing every available avenue towards the digital storefront.
Emails show Microsoft was willing to ‘turn Xbox-exclusive games into iPhone apps’