A number of good pieces have been written now about the phenomenon of "viral" Web traffic hits where a handful of outlets (Upworthy, Viralnova) have gotten really good at identifying and marketing pieces that explode. Gawker's Neetzan Zimmerman specializes in viral hits and dominates the Gawker media leaderboards. And, of course, there's BuzzFeed.
We are touched by the same viral virus here at Slate where Katy Waldman's writeup of the Goldieblox ad scored incredible numbers.
From a business viewpoint, I think an important point to make about this is that "viral" basically just means "is popular on Facebook" since Facebook is really the only host for viral content that matters. And that in turn means that all the viral traffic a website gets is really Facebook's traffic. It's been clear for a long time now—like going back to well before there was an Internet—that journalism just isn't that popular. Most households in the New York City metro area never subscribed to the New York Times, for example. Facebook, by contrast, is something that people really like. So since Facebook is so much more popular than journalism, it turns out that the most popular kind of journalism is Facebook content.
But this is still really Facebook's traffic. Not just in the sense that Facebook can always tweak the algorithms that determine what plays well on Facebook, but in the sense that whatever economic value is created by "viral" content will ultimately be captured by Facebook. If you want to advertise to an audience of people eager to consume Facebook-friendly content, after all, the logical place to do that is on Facebook.