Forty years ago Playboy invented a magazine format that had a major impact on American culture, and it had nothing to do with bare-naked ladies.

We're talking about the Playboy interview (the magazine itself was founded 10 years earlier by Hugh Hefner), and it all started with a 1962 Q&A session between jazz legend Miles Davis and soon-to-be legendary writer Alex Haley.

With such an auspicious beginning, it's easy to see why the adult magazine was able to accumulate a portfolio of notable personalities, from world leaders to American icons, including Cuban dictator Fidel Castro, President Jimmy Carter, rock legend Bob Dylan and author Ayn Rand, for its profiles.

"The Q&A format has been around for centuries in one form or another," said Michael T. Carr, president of Playboy publishing. "But no one has done it in as in-depth a standard as Playboy. If you look at a Barbara Walters interview today, there are maybe seven questions. The Playboy interview is seven to 10 hours."

And with so much time devoted to its subjects, there have been several memorable moments.

Most famous, or infamous perhaps, was a November 1976 interview with then-presidential candidate Jimmy Carter. In it, Carter said, "I've looked on a lot of women with lust. I've committed adultery in my heart many times." The quote caused such an uproar that it almost cost him the election.

In 1967 Fidel Castro told Playboy he believed "all leadership should retire at a young age." At age 75 he's still ruling over communist Cuba.

And in this September's issue, Oracle CEO Larry Ellison -- the fifth richest man in the world -- tells Playboy that Microsoft chairman Bill Gates would "like to co-opt the English language … Bill would explain why MS English is better and he'd make it available to everyone at a very low cost."

But don't expect that quote to have quite the same impact as Carter's did. According to Syracuse University pop-culture professor Robert Thompson, there are so many choices for consumers to get information these days, the Playboy interview is no longer as significant as it once was.

"And not just because of 24-hour cable," Thompson said. "All of these magazines and Internet sites offer quick alternatives to consumers. It's kind of like TV Guide. They were once at the center, but now pop culture is fragmented in so many pieces, and they're just one of them."

The numbers seem to agree. Playboy's circulation once reached a peak of over seven million in the '70s per month. Its current monthly total is around 3.1 million -- and those millions subscribe "for the articles," by the way.

Still, those numbers are very good in an industry where magazines like Gear and Maxim are giving the old stalwarts like Playboy and Esquire a run for their money.

But Carr said he's not concerned about competition. "Often duplicated, never copied," he said. "When Hugh Hefner came on the scene, Life, Look, the Saturday Evening Post were on top. They no longer exist. Playboy has stood the test of time."