Geohot, a notorious iPhone hacker, just released his own jailbreak for the iPhone 3G S just before the iPhone Dev Team with a tool named Purplera1n. Right now, it only works for Windows and a Mac version should be release pretty soon. The jailbreak is really easy to do, and pretty painless. Just a reminder: This won’t unlock your iPhone 3G S, but you will be able to do the all the jailbroken fun of the iPhone. After you jailbreak, just go into Cydia and add the iPhone Dev Team Repo for Ultrasn0w and you’ll be good. Or you can just use redsn0w. Alright, let’s get to it then!
Step 0: Make sure your Wi-Fi and/or 3G/EDGE connections are set up properly. Make sure you do a FULL Backup of your iPhone before continuing.
Step 2: Verify that you have iTunes 8.2 installed. After installing make sure you have OS 3.0 on your iPhone 3G S. Close out of iTunes.
Step 4: Connect your iPhone to your computer with the USB cable. You DO NOT need to be in DFU mode because the jailbreak is so small in size.
Step 8: If Cydia does not appear, reboot your iPhone and try again.
That’s it! Mad props to GeoHot!