This is a totally biased opinion, because I'm in love with Jon Stewart.
But I was just listening to Fresh Air with Teri Gross, and she had one of the executive writers from the Colbert Report on - it sounds like they have to work really really hard to create that show, which gives me even more respect for it. She said writing for that character is like "swimming while looking backward" or something...meaning, to try to write that conservative of a character is like taking what you really believe and doing the complete opposite.