A mounted device is displayed in Places menu.
If you unmount it it disappears.
It would nice if the places menu has the same behavior like the memo sidebar and shows unmounted devices.
A click on an unmounted Device should open and mount it by the default file manager.
This is available in one of the applets, I remember.
Can you please check if this issue persists in latest Cinnamon 2.2 (Mint 17) ? Please close the defect otherwise.
This works wit Places Center and Cinnamon 2.2