When you start with the app you can leave all of yourmessage history in the inbox (if, like me, you are not in the habit of archiving or filing it) or you can choose one of the archiving options (archive everything, all except unread or all except starred).
If you still manage to leaveyour favourite jacket behind, it will send you a text, email or Facebook message with the GPS coordinates of the last known location so you can track it down on Google Maps.