Hmm. The lock vulnerability is pretty interesting. I don't know why I didn't come up with that idea myself, since it's so simple.
I've run a few numbers on the problem, and it appears that even if you have some pretty nice locks with 100 million possible keys, you can find a master key with only 40-80 tries. Of course, I hear that locksmiths have plenty of tricks that are even more effective than that..
I'm wrapping up stuff at work (sort of -- there's some documentation that I've been avoiding writing). Last day will be tomorrow, barring something strange happening out of the blue.