Hmm, yeah, Bookmarks is supposed to be package scoped, however there seems to be a bug (at least in PG) that makes it not be so at the moment. The scoping is supposed to come from the root_folder_id. I notice that different package instances indeed have different root_folder_ids but yet the bookmarks are shared. The index page query is quite involved and it's not obvious to me what's wrong with it.
