Watching Jon Stewart has diminishing returns. Yeah, you can insert a joke here if you like. Seems too easy, so I'm gonna move on.
There's a new study out, though, that finds watching Jon Stewart's The Daily Show leads to greater attentiveness to the news, but the more you watch, the less of an effect it has. The International Journal of Public Opinion Research article also notes that one-out-of-five viewers have little interest in politics -- fascinating given the content of the program.
A major point gets to the crux of the argument between those who believe enertainment news programs either fail to inform, or actually do inform, some people. This article falls on the "inform" side, suggesting that many with no interest are exposed to some news and information, thus leading to greater attentiveness and, I suppose by default, greater knowledge.