This is an interesting article on comedians blurring the line between policy and humor.  I like the idea of Stewart and Colbert as court jesters especially:

Comics like Mr. Stewart and Mr. Colbert are also returning the comedian to the role once played by the court jester, who was allowed to speak truth to power with impunity. Professional fools are spies in the house of power; they can go places few other people can. Recall the Fool confronting King Lear: “Thou shouldst not have been old till thou hadst been wise.” Of course, unlike the nonpartisan Fool, Mr. Stewart and Mr. Colbert have their (mostly) liberal politics, and if you don’t share their attitudes, these serious, polemical comedians can seem unbearably knowing and clubby. That is both the annoying limitation and the refreshing gamble of confrontational, interactive comedy. It shows its cards.