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.
Right now it looks like you can jailbreak an iPhone 4, first generation iPad or an fourth generation iPod touch using these tools. Support for additional models is on the way.
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.
Update: It’s also now possible to jailbreak iOS 4.3.1 on a Windows computer using Sn0wbreeze. The original method required a Mac.
The last paragraph is completely opposed to the facts: you can not downgrade the baseband firmware to an unlockable version.
Yes you can. Jeff on JailbreakMovies.com explains how, and it worked 100% for me.
Paid for jailbreak and unlock online is a scam! grey Sim work but keep lost connection :(
Windows users can use Sn0wbreeze http://www.newsden.net/?p=7443/
Has anybody tried on their ipad?
It’s sn0wbreeze, not ultrasn0w that you use to Jailbreak.
Ultrasn0w is for Unlock.
I jailbroke my iphone 4.3.1 using the method here http://surreystore.com/Forums/tech-help/how-to-jailbreak-ios-4-3-1/
have anymore tried downgrading? and did it works?