The note being in your inventory allows you to click the note feature in the buddy/friend list ui to send notes. The description of the note could use some fixing to properly describe this.

Sorry about that! The Note's description was wrong - it isn't double-clicked. Keep the Note in your inventory, open your Buddy List, click a buddy and press NOTE; one Note is used per note sent and your buddy reads it at their next login. The Note's tooltip now explains this (live now).