U2 IS SET TO perform tomorrow night on the season finale of "American Idol."

It should be an interesting juxtaposition: A long-running band that writes its own songs and frequently has something to say rocking out against the backdrop of a glorified karaoke show that has nothing to say.

While backstage at the Billboard Music Awards, U2's longtime manager, Paul McGuinness, told Billboard.com that the group would rehearse for the "Idol" finale last night and perform on the show tomorrow.

Tonight, U2 will perform its stadium show in Salt Lake City.

Tomorrow night's "Idol" will also reveal whether Scotty McCreery or Lauren Alaina is the Season 10 champ.

And then we'll find out who wins "The Voice," and then "America's Got Talent" will start, and five years from now U2 will still be bigger than all of the winners from all of these shows.

Tattbits

* "Friends" star David Schwimmer is now a father.

A spokeswoman for Schwimmer said he and his wife, Zoe Buckman, recently welcomed their first daughter, Cleo Buckman Schwimmer, who was born May 8.

* Michael Lohan, troubled Lindsay Lohan's troubled father, has pleaded not guilty to attacking his ex-girlfriend during an argument earlier this year in California. He was arrested in March after ex Kate Major accused him of abusing her and preventing her from calling 9-1-1. Trial is set for July 5.

* If you're a "Dilbert" fan, you'll probably head to Page 32 right after you finish Tattle (online readers may disregard the page-number references.) In a new tech innovation, "Dilbert" fans, who reside in their own bizarro-world corporate jobs, will now be able to swap places with the eternally befuddled office drone and his not-so-sharp cubicle dwellers.

Peanuts Worldwide, the marketing agent for Dilbert, says readers will be able to personalize up to 25 separate Dilbert comic strips with their own images and share them online with others.

Using technology created by PixFusion, readers can upload a photo to pixfusion.com, select an animated strip and become Boss, Wally, Alice or Carol.

* The Hollywood Reporter says that after this season, Showtime has canceled "United States of Tara," about a mom who suffers from multiple personalities.

No they haven't.

Yes they have.

Worst move ever.

It's about bleeping time.

This year's premiere drew only 411,000 viewers.

Nearly that many philly.com users read David Gambacorta's story on John Bolaris.

Showtime also announced yesterday that Edie Falco's "Nurse Jackie" will be back for a fourth season.

* Tattle is certainly pleased that the Four Horseman of the Apocalypse have decided to keep their horses in the stable a while longer, but parts of this doomsday silliness really ticked us off.

Doomsayer Harold Camping, 89, whose dire Magic 8 Ball prediction financially ruined many of his followers, couldn't bring himself even to say he was sorry - as if one should be sorry the world didn't end.

Camping instead said he was "flabbergasted" that the world was still here and was looking for answers. Unfortunately, he thinks he found them, and the end is now coming Oct. 21.

Sorry, Phillies, that's two games into the World Series. We can't even say wait 'til next year because there won't be a next year.

Even more disturbing, however, was the comment from Camping publicist Tom Evans, who, according to "The Lookout" on Yahoo! told the Los Angeles Times that Camping's followers were "disappointed" that 200 million true believers didn't get to take their magic-carpet ride to Heaven Saturday, while the rest of humanity died from earthly famine and destruction.

Yup, nothing disappoints a true believer like a lack of earthquakes and pestilence. Someone in the Camping camp must have gotten a real rush out of that Missouri tornado. Granted, when you cover celebrities, it's difficult to have much faith in anything, but it's hard for a lowly gossip columnist to imagine a benevolent God wanting billions of people to suffer tragic, painful deaths because they didn't heed the advice of a radio preacher. Heaven forbid you miss THE MESSAGE because Camping isn't syndicated in your area.

Daily News wire services contributed to this report.

Email: gensleh@phillynews.com.