The best part about this jailbreak is that it is untethered jailbreak...NOW YOU CAN FINALLY reboot your iPad without having to jailbreak it again. With earlier jailbreaks, whenever you rebooted your iPad, it would go into DFU mode requiring another jailbreak it to refresh it.
For those that have been relying on ultrasn0w for a carrier unlock on the iPhone, you should hold off on this jailbreak as it will update your baseband and likely lock your iPhone.
Instructions to jailbreak your iPad, iPod Touch or iPhone...
Step 1: Download greenPois0n from this link.
Step 2: Connect your iPad with USB to your computer and click “Prepare to Jailbreak (DFU)”
Step 3: Follow the onscreen instructions to enter your iPad into DFU mode:
- Press and hold the sleep button (2 seconds)
- Continue holding sleep; press and hold home (10 seconds)
- Release sleep button; continue holding home (15 seconds)
Step 5: Your iPad is now successfully jailbroken on iOS 4.2.1. Start “Loader” found on the homescreen to install Cydia. Be sure to check out the ThemeCenter and new manage account features in Cydia as well.