Hitwise released figures for the week ending March 13, 2010, naming Facebook as the most-visited Web site in the nation, trouncing Google. It's not the first time this has happened, but the difference was markedly more dramatic. According to the site, Facebook's market share increased 185% last week, compared to the same week in 2009, while visits to Google were up 9% in the time frame. Together, Facebook and Google accounted for 14% of all U.S. Internet visits.
No verifiable stats on how The Smoking Nun ranked, but I think it's safe to say we weren't No. 3.