Shepard Fairey may have hoped to teach something new about art and copyright with his iconic "Hope" poster of Barack Obama. Instead, he is accused of lying about which Associated Press photo he used. (He says he made a mistake.) But if Fairey's lying has probably made a hash of his case and lost him a lawyer, it has also raised that pesky question yet again: Just what is fair use? Was it legal for Fairey to take an AP photo and turn it into this piece of artwork?