http://www.annenbergpublicpolicycenter.org/naes/2004_03_late-night-knowledge-2_9-21_pr.pdf(PDF warning)
That's a link to a survey by Annenberg that indicates that the "Daily Show Effect" may be the best thing happening to Americans. According to the survey (yeah, yeah - it's just a stupid survey, I get that), Daily Show viewers were the most knowledgable news watching audience around among the 18-29 year old demographic.
It's kind of silly when you step back and look at it. But silly in interesting - how do the dots really connect - kind of way.