The terms of the deal were obviously worth considering. But here's an alternate take on the rejection: Zuckerberg and his board remember speculation that Facebook predecessor MySpace could eventually be . The number came from an analyst at RBC Capital who had met with an executive from Fox, MySpace's parent company.

And while it's not a straight comparison, Skype's management landed a $2.6 billion purchase from eBay for a much smaller customer base and not much of a revenue model. By contrast, Facebook has advertisers and marketers paying real money to cover the site with ads and applications.