DevTeam recently released new version of redsn0w to jailbreak iOS 4.1. New RedSn0w 0.9.6 b1 supports iOS 4.0 and iOS 4.1 running on iPhone 3G or iPod touch 2G.
There is only Mac OS X x86 version, that you can download here.
Select your stock 4.1 or 4.0 ipsw (you’ve already used this to update your device to 4.1 or 4.0)
Select “Install Cydia” and any of the other options shown above, then click “Next”. Use DFU mode to install the jailbreak.
As usual DevTeam reminds us: IF YOU USE THE ULTRASN0W UNLOCK, PLEASE WAIT FOR PWNAGETOOL TO SUPPORT 4.1. DO NOT USE REDSN0W
That’s because to use redsn0w at 4.1, you need to already have updated to official 4.1 from Apple. If you do that, you lose the ultrasn0w unlock (possibly forever).
iPhone 2G and iPod touch 1G do not officially support iOS 4. However there is a project called WhiteD00r that aims to bring iOS 4 functionality to iPhone 2G users with a custom firmware bundle.
This bundle is created by Matteo Morando and is based on firmware 3.1.3. It is built with PwnageTool. It incorporates several utilities to adds iOS 4 features such as multitasking, wallpaper, tethering, sms count, and more.
There are 3 different versions -- Lite and Full for iPhone 2G and one for iPod touch 1G. Here is the complete feature list:
