I'm going to just blatenly rip off Time magazine on this:

He says he's just a goofy dork on a silly network, with prank-calling puppets as his lead-in. But when it comes to events like Sept. 11, the Iraq War and Monday night's post-assassination processing, Stewart has increasingly been turned to as not just the man to mock the absurdity of our media-political machine, but also to make sense out of the madness. Whether he recognizes his role or not, Stewart has become an influential barometer as to the seriousness of an offense (Rick Sanchez), the merits of an argument (John McCain, on “Don't Ask, Don't Tell”) and the hypocrisy of lawmakers (the 9/11 health care bill). And every once in a while, in moments of startling sincerity and intimacy, he has also embraced the challenge of trying to process a nation's fear and pain.

In fact, over the span of a decade, he's done the latter so well that we now look to him for our dose of sanity amidst the chaos: