The Ergotron Dock Locker, available later this month, is a stand for your Surface Pro 3 that connects to any surface you choose through a screw or bolt, and then keeps the device secure through a keyed lock when inserted.
"As a tablet stand, the Dock Locker maintains the screen's position for working, combining a comfortable viewing angle with a stable touchscreen interface.
Attach the Dock Locker to any surface up to 1.5" (3.8 cm) thick with choice of provided bolt-through or screw-in hardware. Or plug your cable lock (sold separately) into the security slot on the top of the unit."
In addition to looking like a pretty good option for storing your Surface Pro 3, the Dock Locker is made by Anthro, the company behind our own Daniel Rubino's standing desk. If you're interested in picking one up, the Dock Locker will go on sale later this month, though pricing is an unknown.
Source: Ergotron Thanks to Anthony S. for the tip!