Playboy magazine, which has seen its circulation plummet 18 percent in three years to 2.6 million from 3.15 million, has put The Simpsons matriarch Marge Simpson on the cover of its November issue and included an interview with her and even a centerfold portrait. Details were, er, sketchy, but the magazine's editorial director,James Jellinek, told the Associated Press that the centerfold is "very, very racy." And at a time when racier fare can generally be found with the click of a mouse on an Internet browser, Playboy spokeswoman suggested that it was the uniqueness of the Simpson character's appearance in the magazine that would lift circulation. "We knew that this would really appeal to the 20-something crowd," she told the A.P. Playboy has apparently been able to persuade some convenience-store outlets to display the magazine on their shelves for the first time in years. The A.P. said that 7-Eleven stores, which have refused to stock it for more than 20 years, has agreed to offer the Marge Simpson issue.