Well, Jon Stewart for one, when he isn't being just a stand-up, does tend to call out major journalistic and political figures for their inadequacies in this regard.
With extreme irregularity (i.e. when it suits him) and a disingenuous tendency to hide behind "I'm just a comedian" as soon as anyone calls him on it.
Well, true, but I've always read that as him not wanting to become the same sort of political lighting-rod that he hates. He was very careful to avoid any overt political associations for his rally, for instance.