Zuckerberg sweats it out onstage over privacy questions at AllThingsD's D8 conference, so much so that he takes off his trademark hooded sweatshirt. He also donates $100 million to the Newark Public School System. "The Social Network" premieres, racking accolades with its compelling, if not-so-accurate depiction, of Facebook's humble beginings. Number of users: over 500 million.
NEXT: 2011