I've heard a bunch of people inside and outside of facebook point this out. Then the reasonable ones say "but the services are very different, twitter is social

I've heard a bunch of people inside and outside of facebook point this out. Then the reasonable ones say "but the services are very different, twitter is social piping and farmville is a game" The impressive stats with farmville show that facebook is huge and also that something like a game can be commonly enjoyable to a huge percentage of the site.