I have an original 2G iPhone that I unlocked and Jailbroke a long time ago with the PWNAGE tool and have been using it primarily on ATT in the US but when I travel to China and Europe I use prepaid SIMs in it for my daily contact (and only get data when I'm within range of WiFi)

I recently upgraded to a 3GS and want to do the same thing but the number of differnet tools here is a bit much. Is there an idiots guide to jailbreaking and unlocking the 3GS? (if it makes any difference, the phone was 3.1.2 out of hte box)