There’s a force in mobile app distribution that isn’t talked about much despite its magnitude: mobile social networks. Mobile social nets are becoming the predominant mobile app paid discovery/distribution platforms. How big is this force? Line, the Japanese mobile messenger with more than 200M users is on a $400M run rate, 60% of which is derived from app distribution. Kakao Talk will pay out about $600M to developers this year - which is about 10% of iTunes global developer payout in 2012.