As we know that Chronic Dev Team has released its Limera1n based “Greenpoison” to jailbreak iOS 4.1 on iPhone 4 and other iDevice it’s a pretty straightforward jailbreak that will work on iOS 4.1 with the iPhone 4, iPhone 3GS, iPod touch 3g, and iPod touch 4G. Here is the complete step by step how-to guide to jailbreak iPhone 4 with iOS 4.1 using Greenpoison. One thing which is important to note here is that do not use Greenpoison if you use UltrasnOw to unlock your iPhone 4 as installing Greenpoison might bar UltrasnOw from ever operating!
Step 3: Switch off you iPhone 4 and connect it to computer.
Step 4: Now click on “Prepare to Jailbreak (DFU)” button & follow on-screen instructions to put your iPhone 4 in DFU mode.
Step 5: When the phone 4 is in DFU mode, you will see the message “Ready to Jailbreak”.
Step 6: Now click on Jailbreak and wait for status bar to complete.
Waiting for the jailbreak to complete, the status bar will indicates what’s going on and the iPhone 4 will reboot itself after that tap on the newly installed “Loader” icon in the home screen, Tap on Cydia and then tap on Install Cydia, Once Cydia is installed you can remove the Loader app, tap on “Remove” and your iPhone 4 will reboot itself once more. That’s it! After your iPhone 4 has rebooted, you will have a completely jailbroken iPhone 4 with Cydia installed on your springboard.