In an Internet 1.0 world "Facebook", would have happened via a 'social' protocol on the Internet just like SMTP, and Zuckerberg would have been a hacker icon just like a Tim Berners Lee.
In this Internet 2.0 world its heading for a 100 billion dollar IPO. I think, its a bad movement of capital. As Facebook was more lucky - timing wise it happened just when broadband Internet was getting prevalent in developing countries of Asia, and many other things.
And unfortunately, it has got no real competition. The only people who are trying to compete (atleast visible to most, discounting efforts like status.net) are Google. Who are just building another Facebook like walled Garden in Google+.
How I would have loved to see a concerted effort from hackers to liberate 'social' to what it should always have been - a protocol!
PS: If mails had happened in Internet 2.0 world. We would have gmail users only mailing to other gmail users and hotmail users only mailing to other hotmail users ... but actually gmail would not have happened as Sabeer Bhatia or Microsoft would have been still ruling the mail world ;-) ... But thankfully it did not turn out that way, as there was already a protocol called SMTP!