updated 09:50 am EDT, Wed July 2, 2014
Supports Kensington, similar locks
Apple has released an official security lock adapter for the 2013 Mac Pro. The accessory connects without tools and supports a variety of Kensington locks, plus locks in a "similar style." While in use the adapter prevents easy access to a Pro's internals.
The item costs $49, and should ship within 24 hours from Apple's online store. While expensive, the product doesn't require any case modifications, unlike some third-party options.