A brand new beta version redsn0w jailbreak has just been released for the iPod Touch 2G and iPhone 3G at FW 4.1 or 4.0, just so you know this update does not include the SHAtter exploit developed by pod2g.
The Dev-Team has put in bold capital letters that if you use the ultrasn0w unlock it would be in your best interest to wait for the pwnage tool to support 4.1, another words do not use redsn0w.
At the moment this new beta version is for Mac OS X x86 only and the Windows version will follow soon enough once bugs have been sorted, you must note (Quote from Dev-Team:
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).
This new jailbreak will not unlock the Apple iPhone baseband; please do post all your comments below as we love hearing from you.
Source – Techtree