The iPhone Dev-Team has recently announced the availability of PwnageTool 3.1, of course as with any jailbreak or unlocking tool — that does come with a warning. Make sure you follow the directions from the Dev Team and read all the directions carefully.
Basically, PwnageTool 3.1 is available, however it is not going to work for everyone just yet. So far those who are using an iPhone 2G (original iPhone), an iPhone 3G or a first generation iPod touch will be able to jailbreak.
As of now, iPhone 3GS users as well as those with a newer iPod touch will still have a little while longer to wait.
Given that jailbreaking has become quite a bit more complicated since the release of iPhone OS 3.0 and now 3.1 I am going to suggest reading the Dev-Team post (which you can find here) before you begin.
Fortunately, and unfortunately I am using an iPhone 3GS so I will not be able to jailbreak with this release. Finally, if anyone is in the same situation as myself, I would suggest holding off on updating (if you have not already) to iPhone OS 3.1.

September 16th, 2009 at 6:32 am
Hmmm, to late – I updated my 3gs to 3.1 when it was released. I’m just hoping the DevTeam come up with a JB soon!!
September 16th, 2009 at 11:23 am
Why the hell are you guys always in such a hurry to dl these new updates ( every month or two lately) instead of waiting just a few days for all the fixes to found!! I have been on the same exact iPhone since 1.1.4 and have always updated and kept my iPhone JB&UNLOCKED to this day but by waiting for all the people who think to be first is best! Actually I should thank you all because the rest of us learn from your mistakesand frustrations!! After a week of you all fighting your phones to get your updates working properly and keeping your phone unlocked/Jailbroken is how the rest of us can simply do this in one or two simple steps with the help of the DEV team ofcourse!!
September 18th, 2009 at 4:24 pm
I’ve also updated my iPhone 3GS. But, it does not require to be unlocked. Just wait for the redsn0w now.
Cheers~~~