Facebook has the same number of users now as there were people alive just a century ago, which is a pretty impressive number of users for a dorm-room project after just a decade. And if you're the guy who did the project, you'd probably want to tout that.
Mark Zuckerberg posted this interesting fact last night (on Facebook):
Fun fact: as many people use Facebook today as were alive 100 years ago. (~1.7 billion people)
Pretty impressive, especially considering that 100 years ago, computers hadn't been invented, most of the population lived without electricity, horses and polio were still a big deal, women couldn't vote, and no one had said the word "selfie."