<VV> The value of keyed locks ...

[Chris & Bill Strickland]

... is certainly in question:

A technique called 'bumping' can open most mechanical pin-tumbler locks 
damage free, in little time, with little training and using only 
inexpensive tools. Even a number of high security locks can be rapidly 
opened damage free with this technique.

US Post Office mailboxes do not offer protection against opening with a 
bumpkey.

video: http://www.youtube.com/watch?v=7Uv45y6vkcQ&search=bump%20key

paper: http://www.toool.nl/bumping.pdf