Inventive users can download the iPhone 1A543a restore image (93MB) from Apple.
The link was discovered through iTunes 7.3, which offers users the capability to restore their iPhone to factory default settings. The resultant .zip file provides a Firmware Folder and two DMG (one password protected).
There have been some ongoing efforts to unlock the Apple iPhone, but no documented success. According to one blogger, the Apple iPhone becomes locked to your SIM which you use to activate it (photo), but the iPhone's SIM can succesfully be used in another AT&T phone.