When it was announced that Facebook had one billion active users that was a milestone. The Social Network was now so big that it defied belief.
Another milestone was breached this week, after Mark Zuckerberg took to his own account to announce that one billion users had accessed Facebook within one 24 hour period. I guess the next milestone will be when we hit one billion simultaneous users.
What strikes me is that Facebook has transcended the idea of an internet service and become a part of life in the frictionless sort of way that mobile phones and landlines became a part of our lives twenty and sixty years ago.