Amy Winehouse better get her act together! The embattled singer is scheduled to perform at the 46664 all-star concert on June 27 in London's Hyde Park. It's not just any old gig: The megawatt event is being staged to raise awareness about AIDS and HIV prevention, and to celebrate Nelson Mandela's 90th birthday. She's not the only brassy lady on tap: Leona Lewis, Annie Lennox and Shirley Bassey will also be serenading the South African leader. Oprah, Will Smith and Robert De Niro are also expected to be on hand to help blow out the candles.