Not much for television myself, I don't know how Jon Stewart normally spends his time. But if his rally was any indication, he markets himself as a reaction against the mainstream cable news model. This format is sensational and alarmist; and although it attracts a certain audience normally and a broader one at the drop of a "crisis," many people don't like it. Stewart and the Comedy Central team have established their brand by acknowledging this fact.
This is all happening within the marketplace, and in some ways it is kind of cool: one business model thrives by challenging what is inadequate about the other. But that's about it. If you like Jon Stewart, you can watch him to find out what is wrong with his competitors -- and there's plenty wrong, so this can be fun -- or you can bear witness to the "hypocrisy" of the political class; for example, as when they are "caught" saying contradictory things to different audiences. The Daily Show exists to make of routine business and politics a kind of entertainment.
In this respect, the "Rally to Restore Sanity" was a savvy way to promote the show in the guise of a traditional political rally on the National Mall. Considering how few outlets there are for political participation by the working class, we can expect some tension between the organizers and the attendees of any such event. The average person probably does not attend a "rally on the Mall" expecting the political equivalent of a "concert in the afternoon"; although I admit to some uncertainty about which they would prefer.