Looking at the numbers, though, I'm not sure it says what you think it says. My impression is that it says that people who are interested in politics -- political humor from Jon, major newspaper websites, O'Reilly Factor watchers -- know more than folks who just passively consume news every now and then (Fox News Channel). That's the way the data looks to me, anyway.
I need to go back and study it some more, because from the abstract at the bottom, titled "Knowledge Levels by News Source", The Daily Show/Colbert Report looks like it's tied or bested in almost every category by folks who read newspaper websites. In fact, if you call the margin of error around 4%, there's really not much difference in the top several items. And I can't believe something like this would be accurate down to 1 or 2 percentage points or less.
http://people-press.org/report/319/public-knowledge-of-curre...