When it comes to the mating habits of female rock singers, today's divas ain't got nothin' on Carly Simon. Taylor Swift may date and dump a dime-a-dozen variety of pop-boys simply to fuel her songwriting, but it's mere kid stuff compared to Carly's affairs. By the time she released her second album, "No Secrets," in late 1972, she had liaised with Cat Stevens, Mick Jagger, Kris Kristofferson and future husband James Taylor - all bona fide artists. Many were hot for the sexy Simon, but the burning question of her career remains unanswered: just who IS she referring to in her career-defining song, "You're So Vain," which topped the charts 42 years ago this month?