President Obama often is greeted like a movie star, but it's his mother who will be the subject of an upcoming documentary.

"Stanley Ann Dunham: A Most Generous Spirit" will go into production next year, with an expected 2011 release, executive producer Mary Aloe says. It's unknown yet whether it will air on television or appear in theaters.

Aloe said yesterday she believes the president knows about the project, and the filmmakers are trying to secure an interview with him.

The movie will focus on Dunham in her role as the future president's mother, as well as her work with micro-finance, helping women in Third World countries.

She died of cancer in 1995 at age 52.

ELLEN REPLACES PAULA ON 'AMERICAN IDOL'

Ellen DeGeneres is dancing her way onto "American Idol," replacing Paula Abdul as the show's fourth judge.

In a release yesterday from Fox and the show's producers, DeGeneres described herself as a longtime fan of the hit singing contest.

Abdul, who announced she was quitting the show amid a contract dispute, had been replaced by a succession of guest judges as "American Idol" started next season's auditions.

DeGeneres, host of a daytime talk show, wasn't among them. She will join Simon Cowell, Randy Jackson and Kara DioGuardi for the ninth season starting in January.

'DANCING WITH THE STARS' PAIR CALL IT QUITS

"Dancing With the Stars" pros Karina Smirnoff and Maksim Chmerkovskiy are no longer in step with one another. Publicist Susan Madore says the pair broke off their engagement over the weekend. Smirnoff and Chmerkovskiy will continue to appear on "Dancing With the Stars," which premieres Sept. 21 on ABC.

CRONKITE HAILED AS 'VOICE OF CERTAINTY'

By all accounts, Walter Cronkite would have loved the war stories swapped and memories rekindled at his memorial service. All that was missing was a bar.

Instead, there were two presidents, broadcasting royalty, a man who walked on the moon and a drummer for the Grateful Dead. President Obama called Cronkite "a voice of certainty" in an increasingly uncertain world, capping a gathering of old friends, including former President Bill Clinton, yesterday at Lincoln Center's Avery Fisher Hall. Cronkite died July 17 at age 92.

Celebrants spoke of Cronkite's dedication to the news, his love of sailing and family, and unexpected relationships — like becoming good friends with drummer Mickey Hart of the Grateful Dead.

HEF FILES FOR DIVORCE AFTER LONG SEPARATION

After more than a decade of separation, Hugh Hefner is filing for divorce from his wife and former Playmate, Kimberly. Court records in Los Angeles show Hefner filed for divorce on Friday. The couple were married in 1989, the same year Kimberly Hefner was named Playmate of the Year.