In a special edition of NBC's Dateline, "Celebrating Joan Rivers" will look back at the extraordinary life and legacy of Joan Rivers, airing tonight at 9pm/8c. Friends and fellow comics will pay tribute to the legendary comedienne and television host, including Kathy Griffin, Dick Cavett, Donald Trump, Don Rickles, Gilbert Gottfried and Lily Tomlin. Kathie Lee Gifford and Hoda Kotb will co-anchor tonight's one-hour special broadcast. "Celebrating Joan Rivers" will also feature memorable moments and interviews throughout Rivers' groundbreaking career, as well as additional reporting on the day she entered Mount Sinai Hospital.