Yesterday marked Facebook's four year anniversary, or to look at it from the college perspective to which the site owes its success: Facebook graduated. Washington Post assistant editor Rachel Dry, who was a senior at Harvard when Mark Zuckerberg launched thefacebook.com from his college dorm room on February 4, 2004, wrote a commencement address for The New Republic. In it, Dry wonders if Facebook is taking "on the big inequities," as Bill Gates -- like Zuckerberg, a famous Harvard dropout -- urged in his commencement speech at the university last year. We wondered the same thing.

Last week, we wrote about how Twitter, our Best Web LittleCo of 2007, was quickly morphing into a viable platform for serious discussion. One can see that happening today, as Super Tuesday primary elections take place across the US and people report and debate the results across Twitter. But what about Facebook? It was, afterall, our Best Web BigCo of last year, one that we called a "company that