Who knew? … Practically nobody.

OK, everyone, raise your right hand, place your left on a bible (or copy of Network World, if no bible is handy) and read these words out loud: “Yes, indeed, I fully expected and told all my friends that social networking sites would not only become wildly popular … but also tidily profitable.”

Liars, you’re all a bunch of liars. Everyone “in the know” giggled when these sites started springing from the ashes of the dotcom bonfire — everyone. … At least it seemed that way to this giggler.

A BusinessWeek Online article explains why the last laugh — or at least the laugh of the moment — is being had by the proprietors of the more popular of these sites.

One tidbit from the story: “Facebook, a site for students, is now the seventh-busiest spot on the Web. … The site’s owners, who started Facebook just two years ago when they were sophomores at Harvard, would want as much as $2 billion to sell the company, a senior media executive told BusinessWeek Online.”

Two billion? Why that’s darn near enough to cover Harvard tuition.