Click to viewThe free software iPhone unlock—the only one that counts— has been finally achieved by the iPhone Dev Team and it has been independently tested. Everyone can now unlock their iPhones for free. The unlock was not achieved by GeoHot, who was credited with the first hardware unlocks.
[UPDATE 11:01 PM EDT: The iPhone Dev Team has given Giz permission to host a mirror of the original file and the source code, as their servers are getting hammered.]
[UPDATED 7:43PM EST]
Gizmodo's software mirror: Download iUnlock here (this is the only original iUnlock file.)
Gizmodo's source code mirror: Download iUnlock Source here
Looking for the tutorial? Better wait for Erica's GUI installer