Update: For iPhone 1st generation / 2G running 3.1.2 go here.
Here are the steps to jailbreak and unlock iPhone 3G/3GS running on OS 3.1.2 modem firmware v 5.11.07 with blackra1n:
Before starting these steps, make sure you’ve updated to OS 3.1.2 from iTunes
GeoHotz blacksn0w is live and We’ve tested it on our 3G with baseband 5.11 and it works like a charm and here are steps to install it:
Before continuing make sure you are on the 05.11.07 baseband. If you are not please update your firmware to 3.1.2 using iTunes before continuing.
To install blacksn0w you need to [...]