"Brüno" is both a confirmation of Sacha Baron Cohen's startling comic brilliance and a proof of its limitations within his current format. The movie is less irritating than "Borat," his last exercise in guerrilla humiliation: Here, instead of simply ridiculing blameless Romanian peasants and unsuspecting everyday Americans, Cohen adds a new target — the great puffed-up world of celebrity and its glittery, often clueless inhabitants. Early on, we see the star at a Milan runway show, interviewing a model about her job. "It's really hard, isn't it?" he asks, deviously sympathetic. When she responds with "It's very hard," you wish the whole movie had focused on the international fabulatti.

But then we'd be deprived of Cohen's spectacular, mega-tasteless physical comedy. His character this time out, as even blameless Romanian peasants must know by now (to their relief), is Brüno, the flamboyantly gay host of an Austrian TV fashion show called Funkyzeit. Brüno is as much fashion victim as fashion arbiter (witness the screaming, tulip-yellow lederhosen). But he's the unquestionable master of his sexual domain, as we see in a hyper-athletic session with a diminutive boy toy in which he makes alarming use of everything from champagne bottles to DustBusters to enema equipment — a sequence that's hysterical far beyond the usual boundaries of an R rating. (There's also a talking penis later on — a real one. Not really talking, but ... well, you have to see it.)

The movie's structure — "plot" isn't really the word — involves Brüno screwing up and getting fired from his TV job. ("For ze second time in a century," he says, with characteristic insensitivity, "ze world has turned on Austria's greatest man.") So he flies off to L.A., reasonably assuming it to be his kind of town. There he acquires an agent (a colorless character), who secures him a part as an extra on the TV show "Medium" (a meandering sequence). Then he's off to an "anal bleaching salon," mainly so he can deliver a bitchy comment about Salma Hayek.

These segments (and another one involving a hapless karate instructor) are surprisingly flat. Other scenes — especially an overnight camping trip with three decidedly heterosexual hunters, and an interlude in which Brüno undergoes Army basic training — feel, at least to some extent, staged. And Cohen's trademark yokel-baiting, while still sometimes funny (and rather courageous in a he-man wrestling match that devolves into gay fondling and an eruption of bottle-tossing audience fury), is no longer as fresh as it was in "Borat." (A looming concern for Cohen would have to be that he's now too well-known to continue getting away with this sort of faux-incognito act.) Most pitifully, Brüno's pants-dropping assault on mild-mannered Congressman Ron Paul returns Cohen's shtick to its wretched "Candid Camera" roots.

But Brüno's visit to Israel, where he attempts to bring Jews and Palestinians together but confuses Hamas with hummus, is prime stuff. And when Cohen trains his savage eye on celebrities, his aim is invariably true. It's a shame that a needling interview with the serenely out-of-it La Toya Jackson had to be cut from the film following Michael Jackson's death. But we still have Brüno returning from an African sojourn with that most-prized of celebrity accessories, a black baby; and then defending his preposterous adoptive-fatherhood before an irate black audience on a bogus talk show.

Best of all, perhaps, is the movie's conclusion, in which Brüno is joined in a recording studio by the likes of Bono, Sting, Slash and Elton John to record a faux charity single of the "We Are the World" variety. (The song's perfect title is "Dove of Peace.") The stars are complicit hipsters, secure in the knowledge that they're actually in on the joke. Which is the part of the joke they're actually not in on.

Don't miss Kurt Loder's reviews of "Humpday" and "Blood: The Last Vampire," also new in theaters this week.

Check out everything we've got on "Brüno."

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