I have a Verizon (USA) iPhone 4S, and I called Verizon to have them unlock the GSM SIM and they did. But they stated I will need to use a non-USA micro SIM and hook my phone to itunes in order to complete the unlocking process.
If you have a used up pre-paid micro SIM from your travels abroad, it would greatly help me out. I do not bring my computer with me on vacation so doing this abroad with a local is not an option
please contact me via email or imessage at -snip-
[ Edit: Sorry, no personal details please. You can use private messages to get in touch. ]