Tangentially, see Microsoft forced to kill off Facebook integration in Windows and Windows Phone (The Verge)
"Only two companies have apps with over 1 billion Google Play downloads, and the other is Google. Today Facebook proved just how big a business replacing SMS can be, as its leader David Marcus announced Messenger has now been downloaded over 1 billion times on Android. It joins Facebook and WhatsApp, and Google’s Gmail, YouTube, Search, and Maps in this very exclusive club.Facebook Messenger On Android Hits 1…Billion…Downloads | TechCrunch
Messenger’s strategy of layering modern mobile sharing features over a speedy texting app has paid off, and it looks like Facebook’s just getting started. With VOIP, video calling, stickers, voice clips, peer-to-peer payments, location, and a whole platform of third-party content creation apps, Messenger wants to own every way you communicate. And it partially is for well over 600 million users."