[Edward Kirk]

Geohot has published his own unlocking software for the iPhone 3GS. Playing off the Dev Team's Yellowsn0w and Ultrasn0w unlocks, Geohot's unlock is called Purplesn0w, and operates in a similar way to the Dev Team's software, requiring the device to be jailbroken so it can be downloaded through Cydia.

Geohot claims that his unlock is superior to that of the Dev Team's:

Wifi fails? Battery fails? Unlock fails? You need purplesn0w, the geohot 3GS unlock solution. Now I know you here a lot about different colors of sn0w, but I'm here to tell you why purplesn0w is the best. First off, what is purplesn0w? It's a soft unlock for your 3GS that I'd actually use day to day. It's not a daemon that takes any resources, and it doesn't add a task to your baseband. It's very close to a true unlock. All it does is patch three files, CommCenter, lockdownd, and your wildcard activation plist(which you need, activate w at&t sim first, no hacktivation support yet). That's it, no other files are installed. Props to Oranav for the at+xlog exploit!
A full explanation is coming soon, but I think you clever reversers out there will see what it does, and see why it's so pristine :-) The payload is radically different from other varieties of sn0w. beta as usual, back up first.

Be sure to have legit activated 3GS
Disable 3G if you don't have it(like T-Mobile).
Add apt.geohot.com to Cydia
Install com.geohot.purplesn0w
Watch for success output in Cydia
Reboot, and enjoy your unlocked iPhone

[LandShark]

Geohot is the da man. Dev team is also awesome.

i dont want them fight each other, then got pissed and quit