Strangely, there is still excitement to be found in what the industry calls 'event television.' In the middle of an interview on Tuesday with the news anchor Brian Williams, President Barack Obama humored NBC by joking that there would be no federal bailout for Conan O'Brien 'if he screws it up.' The quiz show 'Jeopardy' on Tuesday devoted a whole category to Conan O'Brien trivia. Even David Letterman couldn't stop making cracks about his former protege's ascension to 'The Tonight Show.' On Wednesday, Letterman parodied O'Brien's debut sketch -- running from New York across the country to Los Angeles -- by sprinting beneath the New York skyline at the back of his own set. Letterman, still a little breathless from the exertion, joked that his mother called him to ask, 'When did Jay Leno dye his hair orange?' The event was less a historic passing of the torch than an intra-network scheduling change: Leno, who a week ago stepped down after 17 years as host of 'Tonight,' will return to NBC in the fall at 10 p.m. O'Brien, anointed by NBC as Leno's successor nearly five years ago, has spent the past 16 years in dress rehearsals on 'Late Night.' Yet it turns out that even the most jaded viewers have a State Fair curiosity about television milestones: O'Brien's first night gave the show its largest Monday night audience in four years. Ratings dropped sharply for Tuesday's show, as could be expected. 'Tonight' still has the highest ratings of any late-night talk show, but the luster of such shows has dimmed considerably in the age of cable and DVRs. Taking over as host is a little like being admitted to NATO after the Cold War era. Even Slovenia is a member. O'Brien, whose strength isn't so much stand-up comedy as it is sending up stand-up comedy, kept making cracks about his new show's downward mobility. On Wednesday he noted that 'Tonight' dates to 1954, which he described as 'a simpler time, when Americans actually watched NBC.' The third night was funnier than Monday's debut, an inevitable letdown despite Will Ferrell's Pharaonic entrance on a sedan chair. Too much energy was spent marking a moment that wasn't really so momentous, and O'Brien isn't the self-celebratory sort. He was understandably nervous on opening night and relied on taped skits that went on too long and didn't allow him to show off his impromptu style. On Tuesday Tom Hanks held the spotlight by making a sporting effort to be funny rather than to sit passively and plug his latest movie. (Even the final gag was his: Hanks let himself be knocked down by a boulder-sized papier-mache meteor.) O'Brien was more spontaneous on Wednesday, and made better use of his sidekick, Andy Richter, brought back from the early days of 'Late Night.' They reconstituted their old skit predicting the future, donning space-suit collars to proclaim that someday 'YouTube, Twitter and Facebook will merge into one super-time-wasting Web site called 'youtwitface.'' (The Twitter trend turns out to be for comedians what the Cabbage Patch doll was in the 1980s: a huge fad that is inherently laughable.) And O'Brien tried to introduce a little of his comic sensibility to the classic 'Tonight' opening monologue. He made jokes tailored to the core audience -- an age group that spans 25th college reunion to assisted living -- about Joan Rivers, Larry King and the Octomom (a new musical about her would be named 'Spermalot'). But he added his own tics and twisted humor, channeling the voice of an elderly crank or interrupting himself and others with horror-movie sounds and off-kilter asides. He tried to throw a curve into the guest appearances, as well. A surprise appearance by Kareem Abdul-Jabbar was topped when O'Brien summoned with the same showbiz fanfare a short, bespectacled graphic designer on the show and placed them side by side. His guest Julia Louis-Dreyfus played a version of her Elaine self as a credit-grabbing, award-crazed television star in a skit that included a cameo by Jack McBrayer, Kenneth the Page of '30 Rock.' O'Brien is seeking a balance between the antic anti-comedy he did for younger viewers on 'Late Night,' and the traditional stand-up routines and comfy couch-side chats that proved so popular for Leno. In some ways the joke is on him: If he is too offbeat, the show's core audience could defect; if he leans too far in his predecessor's direction, he wouldn't leave Leno fans much incentive to stay tuned after Leno's show ends. And O'Brien's comedy is hard to pin down. He's a conceptual comedian raised in The Harvard Lampoon/'Saturday Night Live' tradition of parody and deadpan detachment, and he is also a physical clown who uses his oddly angled face and beanpole body as a prop. Some of his best comic bits of the past, like the re-enactment of a 1864 baseball game, make full use of his long limbs. He regularly points out his uncanny resemblance to both the British actress Tilda Swinton and the president of Finland Tarja Halonen. He gave his new audience a taste of how much he relies on silly gestures this week, acting out Gov. Arnold Schwarzenegger biting into a sausage or tracing his upper lip to signify a Frenchman's mustache. 'People at 11:30 have to learn what I am miming,' O'Brien said in an aside. 'It's going to take a long time.' Actually, though, he has only until the fall. 