At first sight it was no contest. On one channel Sarah Palin, the poster-girl of the American right, was wowing audiences with her first routine as a stand-up comedian. On a rival chat show Mitt Romney, the early frontrunner for the Republican nomination in 2012, was delivering such dull fare that his host yawned. Writing a book and promoting it on late-night television have become an integral part of a presidential campaign launch. It certainly worked for Barack Obama. For Romney, the tactic seems to have backfired. He may be ahead of Palin in the opinion polls. But 5.8m people...