Sony doesnt own the Blu Ray Disc Patents. In fact Sony is apart of the Blu Ray Disc Association which is a collection of companies from Apple to Warner Bros. as Board Members and any company can join in for an annual fee of 20,000. which means Microsoft can join and not pay royalties or with the recent rumours of them looking to acquire part of Dell they would then become a Board member which in turn means they definitely won't have to pay royalties