We’ve released a beta version of redsn0w for the iPhone3G and iPod Touch 2G at FW 4.1 or 4.0. It uses the same pwnage2 DFU-mode exploit that we’ve been using since the 2.x days. It does not include the SHAtter exploit developed by pod2g. Nothing new is revealed to Apple with this jailbreak.
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).Note: if you have an “MC” model of the ipt2g, your 4.1 jailbreak will be tethered…sorry! (Consider rolling back to a FW supported by jailbreakme.com or spiritjb.com)
If you have any questions or problems, check out MuscleNerd’s Twitter feed (but please, don’t spam him), or read through the thread comments.