No, it's not a new Gucci wannabe. It's the fact that, for only the seventh time this year, the seemingly invincible Da Vinci Code has been knocked off its perch atop PW's fiction list. (Six of those seven books held the #1 spot for only one week; John Grisham's The Last Juror managed a two-week stint back in February.) Now comes Trace, Patricia Cornwell's 13th work to feature medical examiner Kay Scarpetta. Putnam launched the book on September 7 (copies in print: one million) with a national TV and print ad campaign; a weeklong New York City media blitz had the author appearing on Imus in the Morning, Today, The Early Show plus national TV and radio satellite tours. Cornwell's latest mass market, however, couldn't topple Da Vinci scribe Dan Brown from the top spot on that list: Berkley's Blow Fly had to settle for second place, with an in-print figure of 1,750,000. Judging from past history, it seems likely that Cornwell's #1 hardcover reign will be short-lived: though her last 10 novels all landed in our top spot, the three most recent titles were unseated after one-week runs.