I posted the same question on the Dibb last week and got this interesting response:
From the TSA website -
Air Travel
Accepted and Recognized Locks
The list below identifies locks that are accepted and recognized by TSA, which means that TSA screeners can open and re-lock these bags for security screening instead of cutting the lock. TSA screeners have tools for all TSA accepted and recognized locks that enable them to open the lock without damaging it if a physical inspection is required.
Some of the locks listed below are specific brands. Other names on the lists are manufacturers that produce a wide variety of locks, only some of which are accepted and recognized by TSA. We recommend that you check the packaging to ensure that it has language similar to "accepted and recognized" by TSA if you plan on using the lock for air travel. Most locks on the market are not TSA-recognized. This list will be updated periodically to provide the latest list of brands that are TSA accepted and recognized.
Brand Name:
Aegis Brands Travel Sentry locks
American Tourister Accessories
Atlantic Luggage
Austin House Travel Essentials
Briggs & Riley Luggage
Brinks Travel Sentry locks
Brookstone Easy Check
Delsey Luggage
Eagle Creek Travel Safe
EasyGo
eBags Travel Sentry locks
Franzus Travel Smart
Kenneth Cole Luggage
Lewis N Clark Travel Sentry locks
Magellan's Travel Sentry locks
Master Lock Travel Sentry locks
Pacsafe by Outpac Travel Sentry locks
Prestolock SearchAlert
Restoration Hardware Travel Sentry locks
Royal Traveller by Samsonite Accessories
Samsonite Accessories
Samsonite Luggage
Sharper Image Travel Sentry locks
Sunco Luggage
Target Embark Travel Sentry locks
Tumi Luggage
Voltage Valet Travel Sentry locks
TSA also has the ability to open luggage from some other luggage and/or lock manufacturers not listed above, although time pressures may require screeners to cut these locks rather than open them because there are many manufacturers, each using multiple master keys. It is very important to TSA that your baggage makes it onto your plane, and we will do everything possible to balance that need with security and customer service considerations. Screeners will always strive to open a bag, if required, without breaking the lock.
TSA website