Time magazine named Bono and Bill and Melinda Gates their "Persons of the Year." The United Nations tapped Angelina Jolie as a goodwill ambassador. Bob Geldof organized the Live8 concert to push the G8 leaders' summit on AIDS and debt relief. What has come to be called "celebrity diplomacy" attracts wide media attention, significant money, and top official access around the world. But is this phenomenon just the latest fad? Are celebrities dabbling in an arena that is out of their depth, or are they bringing justified notice to important problems that might otherwise languish on the crowded in