NooB iPhone 3gS question

Hey guys, I am currently using an iPhone 3Gs w/ firmware 3.1.3

For the last 2 years I was on T-Mobile here in the States and always used pwnage tool to unlock and jailbreak my iPhone 3G, beginning of this year I decided I was sick of the piss poor service TM was providing so I made the jump to At&t and got the 3Gs, I have never tried to unlock or jailbreak my 3gs and I am missing some of the things that I used to really enjoy so I am here hoping that someone can at leats point me in the right direction of where to go to get this done, I am pretty familiar with the old process and I used pwnage tool,

Any advice would be greatly appreciated! Also looking forward to getting my 4 in a few weeks!!!