Another bad omen for Yahoo: The Web site that once dominated the Internet has now fallen to third place in the U.S., behind the seemingly untouchable Google—and now Facebook. The shift came in January, when just-released figures show that Facebook’s slight upturn—when coupled with Yahoo’s slight but continued slide—gave Mark Zuckerberg’s Web site the edge. Facebook, which just celebrated its 400 millionth user, receives almost 134 million unique visitors per month, while Yahoo has slipped from dominance to a still-impressive 132 million. Google, for its part, has been mired in controversy over its new venture, Google Buzz, which takes aim at Twitter and Facebook by offering a social-networking side to its colossal Gmail customer base. Let the status updates war begin!