Current version support browse of Users, Roles and their privileges (but this feature is available only if you are database admin, i.e. you have DBA role).
Or do you mean object priveleges from object's side? I.e. to be able to see who has permissions on certain object (table, package, etc)?
BTW USER_TAB_PRIVS contains privileges only for current user, so we use ALL_*_PRIVS tables to get more info. From the other hand some ALL_ tables are accessible only for administrators.