I actually don't have a problem with Time's choice. You got to give props to someone who comes up with something that 1 out of every 12 people in the world subscribe to. 550 million. Yes, Christianity, Islam, and Hinduism (but not any other religion) are each larger, but on the other hand, they've been around for thousands of years. Facebook? Totally non-existant even ten years ago.
The funny thing is, like the movie said, we still don't really know what it IS yet. I mean, it is a place for people to connect. Is that it? THEN what?
On the other hand, maybe that's it. When people hooked up to the Internet in the 1990s, it was a vast crowded oasis of, well, everything. Too much of everything. And Zuckerberg, in his own way, brought order to it — or, at least, to how we reach out to each other on it.
So yeah. Time's Person of the Year. Why not?