When in a course, in the breadcrumbs navigation moodle currently displays something like:
mysite >> course
Instead of the more logical:
mysite >> category >> subcategory >> subcategory >> course
The new proposal would allow easier navigation between courses within the same categories rather than have to return to the first page every time.
Issue discussed in forum posts here http://moodle.org/mod/forum/discuss.php?d=16850