iPhoneInCanada has news of redsn0w, a mac tool for iPhone 3G and iPod Touch 2G 4.1 Jailbreak.
You heard them. Don't jump to 4.1 thinking you can unlock again once you jailbreak, that's NOT the case. If you use ultrasn0w for your unlock, stick with 4.0 and wait it out. Make sure to follow the instructions on the blog and wiki before doing anything. Windows version needed a little more testing but it's confirmed to be coming soon.