Demi Moore is trying out a new role: guest editor in chief. Moore will oversee Marie Claire magazine’s millennium issue, scheduled to hit the stands Nov. 5. “Demi has a great sense of style, a sense of humor and a sense of justice. She has beauty and brains,” said the magazine’s normal editor in chief, Glenda Bailey. Guest editors are nothing new in the magazine biz. A few years ago Roseanne oversaw a special issue of the venerable New Yorker, and only recently Marie Claire itself hired a guest editor: Monica Lewinsky.