Chronic Dev Team has released a new iOS 4.2.1 jailbreak that is untethered, meaning you will be able to reboot your phone without connecting it to your computer first. GreenPoisOn RC5 only works on Mac OS X, but a Windows version should be coming soon. You can use this new jailbreak for just about any iOS 4.2.1 device, including: iPhone 4, iPhone 3GS, iPad, Apple TV 2nd Gen, and iPod 2nd (2nd, 3rd, and 4th gen).
If you rely on carrier unlock on your iPhone 4, you do not want to update to 4.2.1 or mess with this jailbreak at all as you will be unable to unlock your phone. The servers are being brutally attacked at the moment, so you may have trouble even obtaining GreenPoisOn RC5 an might consider waiting a while. Some have had trouble during the initialization phase. If you’ve used the 4.3 beta, you may also have trouble.
Another important thing to note here is that it’s quite possible, although definitely just speculation, that iOS 4.3 will launch sometime within the next few weeks. Check out the video for instructions on running the exploit.
via Redmond Pie