The Dev-Team have released a redsn0w beta Jailbreak for iPhone3G, iPod touch 2 on iOS 4.1 and iOS 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, they tell you to wait for pwnagetool as redsn0w requires you to update with Apple's firmware which might shut down the possibility for you to unlock "forever".

[Dev-Team Blog]