I think Facebook's primary source of revenue is advertising too. Facebook is taking the stance what Microsoft took a few years ago - getting in the way of it's

I think Facebook's primary source of revenue is advertising too. Facebook is taking the stance what Microsoft took a few years ago - getting in the way of it's users and making choices on behalf of them. On the other hand by being open, Google has made a ton of money from it's competitors like Groupon which spends a big chunk advertising on Google. I don't know if Facebook has made an official comment on this but from here on I think things might get interesting.