Update: Tools are now available for an untethered jailbreak of iOS 4.3.1. You can download the latest software from the iPhone Dev Team, and follow our step-by-step tutorial for jailbreaking an iOS device using redsnow.
The new method is much simpler than the one described below, and you don’t need to plug your device into a computer every time you want to reboot. Unfortunately the new tools don’t yet support the iPad 2.
Original article: There’s good news and bad news for anyone who wants to upgrade their iPhone, iPod touch, or iPad to the latest version of iOS, but also wants to be able to jailbreak their device to run apps that aren’t supported by Apple. The good news is that you can jailbreak iOS 4.3.1. The bad news is that the process is rather long and complicated, you’ll need to connect your device to a computer to reboot if you don’t want to lose your jailbreak, and there’s no support for carrier unlocking, which means if you’re using your iPhone with an unsupported network, you should probably just hold off on updating to iOS 4.3.1. altogether.
The latest operating system update provides minor bug fixes, addressing a graphics glitch on the latest iPod touch models and some other bugs affecting iPhones and iPads. But if you need a carrier unlock or if you wand an “untethered” jailbreak which lets you reboot without a computer nearby, you should probably hold off until hackers release new jailbreak tools.
That said, if you just can’t wait, Redmond Pie has step by step instructions for jailbreaking iOS 4.3.1. The process involves modifying the PwnageTool software, modifying the iOS 4.3.1 firmware, loading it onto your mobile device, and performing a tethered boot. It’s not for the feint of heart.
Redmond Pie also has instructions for downgrading from iOS 4.3.1 to an earlier version of iOS if you want to use carrier unlock features or a different jailbreak tool.