Now a client of Dave Larabell of the David Black Agency (after leaving behind David Vigliano, Sterling Lord, Dennis Holahan and Mort Janklow), Joe McGinniss hopes to turn his cover story on Sarah Palin for the now-defunct Portfolio magazine into a book.NYO Representatives for Usain Bolt, world-record holder and Olympic Champion in the 100m and 200m sprints, are in talks with unnamed publishers about a possible biography.AP