Comedians posthumously honor George Carlin for Mark Twain prize

George Carlin, who died in June, posthumously receives the Mark Twain Prize for American Humor tonight from the Kennedy Center, with Jon Stewart, Bill Maher, Garry Shandling, Lily Tomlin, Denis Leary, Joan Rivers, Lewis Black, Richard Belzer, and Margaret Cho among those celebrating the late comedian in Washington, D.C. PBS will rebroadcast the ceremony.