Media Bistro report that:

James Patterson Sets World Record

With 31 hardcover novels reaching number one and 45 total books on the list, author James Patterson has earned the Guinness World Record for the "Most Entries on The New York Times Best-Seller List."
Guinness will bestow the award today (Saturday May 30th) at BookExpo America in New York City.

The record will be recorded in "The Guinness World Records 2010," which comes out in September.