I've added span tags with css classes for the levels to the OU nodelet output. Feel free to style it as you like. It is quite frankly way to much of a pain to get it "right" for all the themes and CSS that people use here so we will have to leave it as a user specified feature.

IOW: use your Display Settings and add some styling information for the classes 'user-level-1' through 'user-level-28'.