By CHRISTY LEMIRE

AP Entertainment Writer

“Full Frontal” is essentially an art-house version of last year’s “Jay and Silent Bob Strike Back,” in which Kevin Smith rewarded his fans for their loyalty by making a movie crammed with references to his previous movies, thereby making them feel smugly in the know.

But “Full Frontal” will be perceived as more prestigious, because Steven Soderbergh is the director, and Julia Roberts and Brad Pitt are amonghe stars.

Like Smith, Soderbergh repeatedly refers back to himself; actors pop up who’ve appeared in his previous films, including Roberts, Pitt, Nicky Katt and Terence Stamp, reprising his starring role in “The Limey.” And characters discuss taping themselves having sex, as in “sex, lies, and videotape,” Soderbergh’s 1989 breakout hit.

Both movies employ other similar tactics, including the movie within a movie, the skewering of Hollywood affectations, and the shameless ribbing of Miramax, the distributor of both films.

But so many Hollywood insider movies have come out in recent years, from “The Player” and “Celebrity” to “Hollywood Ending” and “The Kid Stays in the Picture,” that by now they have nothing new to say – and neither does this.

Soderbergh’s technical approach isn’t exactly new, either; he’s basically made a Dogma 95 film, shot in 18 days, mostly on digital video, using natural light. Under a strict set of rules, he had the stars drive themselves to the set, choose their own wardrobe and do their own hair and makeup – just like the rest of us do every day! How life-affirming.

Yet it’s hard not to appreciate Soderbergh’s decision to make a small, experimental film after winning a best-director Oscar for “Traffic,” and enjoying a string of critical and commercial hits, including “Erin Brockovich” and “Ocean’s Eleven.”

The average person (or non-Hollywood insider) may think, “Julia Roberts and Steven Soderbergh together again – I liked ‘Erin Brockovich,’ so I’ll like this.” But they won’t get a lot of the jokes, and they may be put off by the structure, which alternates between what’s supposedly reality, shot on video, and the movie within the movie, shot on film.

Sporadically, though, at its most ad-libbed and deadpan, “Full Frontal” is extremely funny – especially when Katt is on-screen, starring as a modern-day Hitler in a play called “The Sound and the Fuhrer.”

The script from Coleman Hough spans 24 hours in the lives of a group of people in Los Angeles, who have some connection to a movie being shot called “Rendezvous.” Roberts and Blair Underwood play Francesca and Calvin, actors co-starring in the movie as a journalist and the actor she’s interviewing. (Confused yet? We’re just getting started.)

David Hyde Pierce (Niles on “Frasier”) plays Carl, a writer for a magazine (on which Pitt is constantly on the cover) the screenwriter of “Rendezvous.” Catherine Keener steals every scene she’s in as Carl’s wife, Lee, a corporate vice president of human resources who slowly crumbles as the day progresses. In her funniest and most surreal scenes, she quizzes employees on the names of African nations and fires personal questions at them before firing them.

When Lee isn’t meeting Calvin for an afternoon tryst, she’s scolding her younger sister, Linda (Mary McCormack), a masseuse who’s agreed to spend the weekend in Tucson with a man she’s only talked to the Internet.

All these characters will meet up – or at least plan to meet up – at the 40th birthday party of Hollywood producer Gus (David Duchovny), a powerful man with some kinky secrets.

While “Full Frontal” is set in a tangible, detailed Los Angeles, it toys with the idea of what’s real, what’s a movie, and what’s a dream – not to the portentous extent of “Waking Life,” but enough to keep you on your toes.

That’s one of the best things Soderbergh achieves here: His movie is constantly evolving. Just when you think you’ve figured out the characters and their connection to each other, more is revealed to us. And the dialogue, much of it improvised, carries the flow along naturally.

“Full Frontal,” a Miramax Films release, is rated R for language and some sexual content. Running time: 101 minutes. Two and a half stars (out of four).