You wouldn't want to make a steady diet of inside-Hollywood satires ("The Player," HBO's "Entourage"), but Barry Levinson serves up a suitably savory morsel with "What Just Happened," a finely observed and occasionally hilarious glimpse at the most treacherous inner workings of Tinseltown.

"What Just Happened" swirls and swivels around Ben (Robert De Niro), a Hollywood producer who, as the movie opens, has just shown up at a Vanity Fair photo shoot for its annual "Power" issue. As Ben's talky voice-over explains, even something as simple as standing still for the camera is freighted with implications. In this case, it's all about how close you are placed to the "O" and "W" of the capital letters that spell out the word in the background.

As it turns out, a stylist winds up putting Ben somewhere over by "P" — aka Siberia. At this point, "What Just Happened" becomes one big, very amusing flashback, giving the audience a firsthand glimpse of how and with what mercurial swiftness fortunes rise, fall and somersault in the crazy, status-obsessed business of show.

It's clear early on that director Levinson, working from a script that real-life producer Art Linson adapted from his own memoir, will attack his subject with feisty brio. Right off the bat, at a test screening of Ben's latest movie "Fiercely," we see Sean Penn take a hilarious stunt-roll down a pile of gravel and die in a hail of bullets, followed by the ultimate movie taboo, his faithful dog getting shot.

In the men's room after the disastrous screening, Ben encounters an agent (John Turturro) who can only muster one feeble bit of praise: "I liked the music." Later, waiting to take a meeting with a serenely cutthroat studio executive played by Catherine Keener, Ben looks at a poster with only a reptilian eye and the figure $810,000,000 on it. "No director, no stars, not even a title," he says to a companion ruefully. The coin of the realm, clearly, is coin.

As gratifying as it always is to laugh at the movie industry's most appalling excesses, the biggest pleasure of "What Just Happened" is watching De Niro deliver one of his most understated and genuinely affecting performances in recent years.

Here he plays a veteran producer who is juggling two ex-wives, two movies with problems, a midlife crisis, a troubled teenage daughter and various agents, studio suits and apparatchiks who give him no end of grief.

While he tries to persuade a moody star to shave off a Santa Claus beard, while he tries to coax an enfant terrible of a director to let the dog live, Ben tries to find funding for his next film, hitting up investors eager to spend fortunes made in "hair" and "dry cleaning."

"What Just Happened" brims with juicy inside jokes and cameos that will be catnip to hardcore movie fans: Bruce Willis and Penn show up in amusing cameos as themselves, Willis channeling his baddest inner bad boy in a turn that may or may not be inspired by Alec Baldwin (Linson produced "The Edge"). For his part, Penn keeps it mellow, quietly demanding a private jet to Cannes so he can smoke on the plane.

As in every film she's in, Robin Wright Penn, who plays Ben's second ex-wife, Kelly, delivers a quietly indelible moment, in this case during a brief but achingly meaningful scene in an elevator after couples therapy. Sometimes silly, often scathingly funny, "What Just Happened" finally possesses a winning mix of toughness and heart.