One of the infinitely awesome things about stand-up comedy is that everyone, even the best and the biggest and the rich and famous among us, has to work at it to maintain a sufficient level of comedic excellence. Witness Jerry Seinfeld, who tapes tonight for Friday's Late Show with David Letterman and worked the New York City comedy clubs over the past week or two honing his routine with as much intent and focus and professionalism as if he were making his TV debut. I saw Seinfeld when he dropped in for a surprise 10-minute set at the Comedy Cellar, and Seinfeld stuck around for Louis CK's set (that's quite a show already!), then had to bolt for another club to work on the set some more. He'd also done Gotham at least once in the past couple of weeks. You can expect to hear him mine our global fascination with our Blackberrys, and possibly other topics, Friday on Letterman. But again, how great to see this. It really should inspire all comics to work harder on their craft.