For those of you with a Google Nexus One who may find your phone in PUK Lock mode (as I did today), the sequence (once you obtain your PUK Code) is as follows:
**05* (PUK CODE) * (NEW PIN) * (CONFIRM NEW PIN) #
The code can be acquired from your mobile provider, and is tied to your SIM. That is, it won’t change as long as your SIM doesn’t change.