PBOS (Processed Book Operating System, or Processed Book Open Source, depending on the lunar phase) is an implementation of some of the ideas in the original essay "The Processed Book". PBOS provides a very rich context for adding value to a Web-based book through multi-user comments, various kinds of connections, and analytical and visualization tools. The results can range from a few, formal review notes for an author, to a crayonesque markup by mobs of postmodern deconstructors, with the visibility of each controlled by the viewer.