La guida è in lingua inglese ma è perfettamente comprensibile in quanto è ampiamente illustrata. Buon divertimento!
Create a folder on your desktop called Pwnage
Download RedSn0w from here and place it in the Pwnage folder. Likewise, download the latest 4.3.5 firmware from below and place it in the same folder.
Once iTunes has finished updating your iPhone to the desired firmware open the Pwnage folder on your desktop and launch the redsn0w application from the redsn0w folder we extracted earlier.
**Windows 7 users may want to try running the redsn0w executable mode as an administrator in Windows Vista compatibility. You can do this by right clicking the executable and selecting Properties from the contextual menu.
RedSn0w will now guide you through the steps to get into DFU mode. You can find more help with DFU mode here
Once this is complete you will be notified that RedSn0w is done. Click the Finish button. When your iPhone finishes rebooting (5 minutes or so) it will be jailbroken with Cydia on the SpringBoard.
Once RedSn0w has finished jailbreaking your device you will need to boot it tethered. Rerun RedSn0w and this time select Just boot tethered right now from the list of options instead of installing Cydia.
*As usual a big thanks to the iPhone Dev-Team for their hard work and contribution to the iPhone community.
**Windows 7 users may want to try running the redsn0w executable mode as an administrator in Windows Vista compatibility mode if you experience any trouble.