Interesting read on why #Microsoft joined #OIN https://www.yahoo.com/news/microsoft-may-relinquishing-billions-android-patent-royalties-141047213.html TL;DR Microsoft is in a transition from a product company to a service company. With Azure they earn a lot of money these days with people running Free Software on their cloud platform. Which means that the threat of software patent interferes with the growth of their services business these days.