Instagram clears 90mm active users per month: http://instagram.com/press/
Facebook quietly disabled opting out of search results back in December: http://qz.com/44261/ahead-of-graph-search-launch-facebook-removed-the-ability-to-opt-out-of-search-results/
But 1.4mm don't care: http://mashable.com/2013/01/17/facebook-loses-active-users/
Foursquare building a real-life PageRank: http://thenextweb.com/insider/2013/01/18/map-of-500m-foursquare-checkins-demonstrates-how-they-built-a-google-pagerank-for-the-real-world/
Twitter grows its certified products list: https://dev.twitter.com/blog/expanding-twitter-certified-products-program