Is this gonna work on your iPhone?
Yes, this method should be working with all iPhones (there are even positive comments from 16GB iPhone owners). Just a note for 1.1.2 OOTB 4.6 BL owners, the BL is gonna be downgraded to 3.9 version (however that doesn’t affect any functionality at all).
Do you need to keep your xxx-Sim (if any) inside the iPhone?
No, this is a pure software unlock method, you should remove it before starting the process.
Why bother and install 1.1.4?
You get all 1.1.3 enhancements (multiple SMS recipients, moving icons around, web shortcuts, Google Maps GPS-like locator). Plus you get the bug fixes from 1.1.4 (better signal strength, correct SMS order etc.).
Connect your iPhone to Mac or PC, and backup/sync your phone with iTunes to save all your personal settings, contacts, SMS etc.
Press the Shift key on PC, or Option key on Mac, and click on Restore in iTunes. Select the downloaded 1.1.4 file.
Close iTunes, and run ZiPhone. Select the “do it all” option from the GUI.
Restore your backed-up settings with iTunes.
This is it, enjoy your fully unlocked 1.1.4 iPhone!
Step 6 (Optional):
You might need to use the Installer, to install first the BSD subsystem, and then the AppSupport (iClarified source) for 1.1.4 if you are on an unsupported country.
This is currently the most simple jailbreak/unlock method.
In case that you encounter any unexpected problems or have other questions, always check the Hackint0sh forum.