I don't know, but it has gotten a lot more awesome recently. They both have.
Stewart is funny anyway, but he's at his best when he doesn't have to try. The Republican machine provides it's own humor. The researchers at Comedy Central manage to find the Conservative blowhards contradicting themselves. All the show has to do is run the clips side by side and the Republicans provide the comedy.
Sad thing is, it would be funnier if it wasn't all true.