It's been a while since we heard from bestselling author Joe McGinniss, but now he has entered the currently hot horse-racing stakes, planning a book on the thoroughbred racing season in Saratoga in late summer, an occasion that is a blend of tradition, high society and racetrack and stable lore. He had originally planned to write such a book at the beginning of his career, more than 30 years ago, but got sidelined. He thought that now, with all the interest in Funny Cide (a Saratoga-owned horse) and the Seabiscuit book and movie, would be a good time to revisit the idea. S&S publisher David Rosenthal and editor-in-chief Michael Korda jointly bought world rights in the book directly from the author and plan to publish in August next year, in time for the 2004 Saratoga season.