Points of clarification:
Is the bootloader more like a BIOS in that it has nothing to do with the OS which explains why it cannot be circumvented by a firmware update? I would figure if it was really a bootloader it would get rewritten by a firmware update.

What is the seczone and how does it relate to the baseband firmware? What determines if a new seczone will get written? Why is it that if I were to ieraser the baseband and write a 1.1.1 firmware to a 1.1.2 OTB iPhone that the baseband is preserved?

I have a 1.1.2 OTB and I want unlock it. I didn't think this update would come with a new baseband, let alone a bootloader that screws everything up.