The iPhone Dev Team is still hard at work on their beta, pre-release version of the yellowsn0w process which runs on Jailbroken iPhone 3G's to unlock the devices from their carriers. The latest, 0.9.5 is working for some folks right now, but others are still experiencing problems including the inability to make outgoing calls (signal drops off). If you're trying and failing, be sure to give the Dev Team your feedback.
In addition, the Dev Team is also girding themselves, and their code, to fend off those who violate the yellowsn0w (and pwnage) license and try to make a buck by re-selling the Dev Team's work to unsuspecting web surfers. Whether you can really go after someone for abusing the license on a unlocking process that is designed to let people abuse the license of locked products shows just how complicated both commercial and non-commercial protectionism and freedom movements have become.
If you're unlocked, or trying to unlock, let us know how it's going for you. If you have any opinions on the debate around freeing commercial hardware and commercializing free software, drop us a comment as well!