It looks like the CDMA lock is done with something called a MSL, or Master Subsidy Lock. It's similar to SIM locks where the carrier can provide an unlock code. The MSL is generated by using the ESN (Electronic Serial Number) and an algorithm that varies based on carrier.

I found information on two different ways to unlock the MSL. The first is via a program that knows the algorithm for the original carrier and spits out a proper MSL code to use. The other method involves reprograming the phone somehow to change the MSL code to all zeros.

Since it's so trivial to defeat the locks on both GSM and CDMA, I wonder if LTE introduces anything new to make it harder.

(and yes, I'm a bit bored tonight, trying to take my mind off the interview a bit)