Nancy Cartwright and a person in costume as Bart Simpson arrive at The Simpsons Treehouse of Horror XX & 20th Anniversary Party. (THE ASSOCIATED PRESS/Alaric Lambert)

SANTA MONICA, Calif. - Forget red.

The arrivals-line carpet leading into Barker Hangar was yellow - appropriate, given the night's honorees: Homer, Bart, Lisa, Marge and Maggie Simpson, all on hand to celebrate 20 years of "The Simpsons." Their series is the longest-running American sitcom, the longest-running American animated program, and it recently surpassed "Gunsmoke" as the longest-running American primetime scripted entertainment program.

"You know, it's really weird," noted Simpsons creator and series executive producer Matt Groening. "I mean, I thought the show would be successful. But the fact that we're still standing here some 20 years later and talking about it is very peculiar. But very happy."

Brace yourself for another "Simpsons" milestone, as matriarch Marge Simpson appears on the cover of November's Playboy, as well as in a three-page spread for the adult magazine.

"Well, I talked to Marge today," said Al Jean, "The Simpsons" executive producer. "She's a little embarrassed. She wanted people to know the photo is Photoshopped. It's really the body of Wilma Flintstone."

The carpet was crammed with guest stars who've lent their voices to "Simpsons" episodes, including Robert Englund, the actor best known for playing Freddy Kreuger in the "Nightmare on Elm Street" movies, and one who appears eager to see more of Mrs. Simpson. "Marge is hot - big hair and all," he confessed. "And I've loved (actor) Julie Kavner (who supplies the voice of Marge) since 'Rhoda.' So, I'm glad some manifestation of her is getting to finally show it off."

"It is hilarious," added "Star Trek" actor George Takei. "(The Playboy spread) is the kind of thing that makes 'The Simpsons' a perennial. It's going to live long and prosper," he continued, laughing.

Some reporters along the yellow carpet couldn't resist drawing comparisons between "The Simpsons" precocious Bart Simpson and the so-called "Balloon Boy," a 6-year-old who was said to be hiding in the rafters of his family's garage following reports Thursday that he was flying over the plains of Colorado in a giant, homemade helium balloon.

Authorities said Sunday that the story was a hoax concocted to land a reality television show, and the boy's parents, Richard and Mayumi Heene, will likely face felony charges.

"Such a perfect 'Simpsons' episode," commented documentarian Morgan Spurlock, who serves as director of "The Simpsons 20th Anniversary Special in 3-D on Ice," which will air in January. "All of that playing out in real time was so unbelievable. But it's America. It was American news at its best. We run with something without having all the facts. We turn it into a big lead story. That's what it's all about."