The Simpsons has been recognized as the world's longest-running sitcom by the editors of the Guinness World Records book.The Simpsons has been recognized as the world's longest-running sitcom by the editors of the Guinness World Records book. (Fox Broadcasting Co./Associated Press)

Coldplay frontman Chris Martin, comedian Sarah Silverman and the late Eartha Kitt are among the celebrities who will turn up during the upcoming, record-setting season of The Simpsons.

Organizers unveiled a list of confirmed guests for the forthcoming 21st season during last weekend's Comic-Con in San Diego.

British singer-songwriter and musician Martin will appear in an episode where, after winning the lottery, cartoon patriarch Homer hires Coldplay to perform a private concert for the family.

Homer, Marge take up curling

An episode of The Simpsons to be broadcast next February features Homer and Marge joining a mixed curling team and playing one of Canada's favourite sports.

U.S. network Fox is counting on the episode to sweep in some good ratings prior to the 2010 Olympic Games in Vancouver, which begin Feb. 12.

Co-executive producer Rob LaZebnik, who spearheaded the curling research and wrote the script, said he originally was going to have Homer joint a four-person bobsled team.

But curling provides a chance for more laughs because it will show Homer and Marge interacting on the ice, he said.

LaZebnik said the episode is surprisingly respectful of curling and the three Canadian writers on the show are excited about the subject matter.

Silverman is set to portray a love interest for mischief-minded son Bart, while actress Anne Hathaway will also return. After appearing last season as a retirement home volunteer who captures Bart's attention, the actress will make a second visit to Springfield.

Canadians Seth Rogen and Neve Campbell will voice characters this season, as will Jonah Hill, the Smothers Brothers and professional football's Manning brothers.

Legendary Far Side cartoonist Gary Larsen and Kitt — who recorded her performance prior to her death in December 2008 — will also be featured.

At Saturday's Comic-Con session, where fans also got a sneak peek at this year's upcoming Halloween Treehouse of Horror special, a representative from the publishers of the Guinness World Records books turned the tables and surprised show creator Matt Groening, producers and the Simpsons cast with a pronouncement.

Craig Glenday, editor in chief of Guinness World Records 2010, revealed that The Simpsons is the longest-running sitcom in the world (heading into the new season with about 450 episodes and surpassing the record held by The Adventures of Ozzie and Harriet ) and the longest-running animated TV series.

The 21st season of The Simpsons begins in North America on Sept. 27. Guinness World Records 2010 is set for release Sept. 17.