Andy Warhol's paintings of Campbell's soup cans might be more recognizable than any other American artwork - and that's just what he intended. They helped banish the solemnity of painters like Jackson Pollock and Willem de Kooning, and established him as an artist despite his limited abilities. But why did Warhol start painting them? And what do they mean? As part of Studio 360's series on American Icons, David Krasnow asks if there's anything in the can.