Inside Facebook Gold, a tracking service that shows country-by-country monthly active user counts, based on the data that Facebook provides in its advertising tool. It showed Facebook US draffic falling from 155.2 million at the beginning of May to 149.4 million at the beginning of June, but growing by 11.8 million monthly actives around the world to reach 687.1 million over the same period.

Available Data Shows Facebook User Numbers Growing Less Quickly, or Slowly, or Falling, an article on Insidefacebook features the above graphic and more details.  Insidefacebook was arguing a day earlier here that "by the time Facebook reaches around 50% of the total population in a given country (plus or minus, depending on internet access rates in that country), growth generally slows to a halt" and illustrates that by showing that current growth in new members is driven by big gains in heavily-populated developing countries like Mexico, Brazil, India and Indonesia." We of course believe that users will more and more use different social media networks for different purposes; say Facebook for friends, LinkedIn for work and something like Toy Collector for their hobby