The dev team has just made available Pwnage Tool 3.1 allowing to jailbreak and customize Firmware 3.1!
It is important to remember that Pwnage Tool only works on Mac!
Currently, this version is valid only for iPhone 3G and Edge! If everything is going well, Redsnow Mac and Win should follow.
However, the owners iPhone 3GS will have to still be patient.
The download link is available in our forum.
We discuss it on the Forum