Appreciation: Carlin, from straight comic to icon

** FILE ** In a July 22, 1972 file photo Milwaukee Police officers lead comedian George Carlin off the Summerfest grounds in Milwaukee, Wis. He was arrested after using allegedly profane language during his act at Summerfest. He used seven words he said could not be used on television. A publicist for George Carlin says the legendary comedian has died of heart failure at a hospital in Santa Monica, Calif., Sunday June 22, 2008. (AP Photo/file)