The Dev-Team would like to let you know that you can now jailbreak iPhone OS 3.1, but only a select number of you. It seems that Apple has gone the extra mile this time to make the Dev-Team's job a bit more difficult, so follow their directions carefully because this could get tricky.
The first generation iPhone, iPhone 3G, and first generation iPod touch are all able to be jailbroken with the newly released PwnageTool 3.1. The catch is that the tool is only available for Mac OS X.
The iPhone 3GS, the second and third-generaiton iPod touch are all incapable of being jailbroken at this time, but the Dev-Team has promised that redsn0w will be released sometime in the near future for Mac OS X and Windows, just be patient.
Here are a couple of tips for you lucky early iPhone and iPod touch users that you should heed before going ahead with the process. Actually, you should probably check out the entire Dev-Team blog post if you are even the slightest bit uncomfortable with jailbreaking. They have a much more detailed breakdown of the process and terminology.
If you are using a 3G iPhone with ultrasn0w and rely on ultrasn0w to obtain cellular service, then you should only upgrade to 3.1 with a PwnageTool created .ipsw. - Stay away from Apple’s direct updates.
If you have an original iPhone (1st generation) then 3.1 unlock works with this PwnageTool release. iPhone 3G users upgrading to 3.1 will need to continue using ultrasn0w with a PwnageTool created 3.1 .ipsw
