The Book title override module is a new module released for Drupal 6 and 7.  This allows you to alter the way the title of a node is presented in the book outline.  This will change the title that shows up in menu hierarchies, next / previous navigation at the footer of pages and breadcumb links.  Check out the tour below for a demo in both Drupal 6 and Drupal 7 implementations (spoiler: they are the same).