Profile - Jon Stewart

US comedian Jon Stewart has politicians queuing up to appear on the satirical The Daily Show. Both Senators McCain and Obama have been interviewed on it. But what is it that makes this TV show so popular, and how is a comedian being talked about as one of the most trusted men in America, and what does his success tell us about US politics and mainstream media? Ahead of the US party conventions and as the presidential race intensifies, Chris Bowlby considers the man who's brought satire to the centre of US political life.