In just the span of a short few years, Jon Stewart has gone from optional to indispensable. Case in point: when Jon went all Glenn Beck on Jim Cramer a few months back. A few of us blanched. Getting pissed, brimming with bile—that was so . . . MSM of him. And yet, in the niche-y, hip, and in-the-know world of late-night, media-skewering comedy, it had the impact of Cronkite turning against Vietnam. The Web clips of the choreographed filleting of Jim Cramer helped foment public outrage against the excesses of the financial industry in the midst of a housing crisis. That was an important moment. But even more important is the system of checks and balances Jon has created. On occasion, when we’ve been on the cusp of doing something completely inane on NBC Nightly News, I will gently suggest to my colleagues that we simply courier the tape over to Jon’s office, to spare the Daily Show interns the time and trouble of logging our broadcast that night. That usually gets us to rethink the inane segment we were planning on airing. The old arc of a news story went like this: News happens. Media cover news. Audience reacts, then turns in for the night. For the past several years, however, there’s been another step added to the end of the process: being held to account for our faults by a comedy show with a sharp eye and a sharp tongue. How did we live without it?