In short words: This add-on creates a second visitor message tab with own permissions (to post staff related notes,..).
You're also able to import your old vBulletin user notes.
ATM the importer imports ONLY the notes and ignores the permissions!
You need to set the permissions manually!
Old release thread: http://xenforo.com/community/threads/ragtek-user-notes.22676/
Github Repository: https://github.com/ragtek/UN