Green Poison: Jailbreak: Greenpoison RC5 to iPhone, iPod Touch and iPad

Geekismo our friends leave us how to perform the Jailbreak Untethered devices with iOS 4.2.1. This version of Greenpoison RC5 supports the following devices: iPod Touch 2G, iPod Touch 3G, iPod Touch 4G, iPad, iPhone 3G, iPhone 4, iPhone 4 CDMA.
Steps:

1. Download GreenPois0n RC5
2. Connect the device to your computer, run Greenpois0n and click on "Prepare to Jailbreak (DFU). "
3. Next you follow all the instructions you will to put your device in DFU mode, press and hold the "sleep" for 2 seconds while pressing the Home button for 10 seconds, release the "sleep" and continue pressing the Home button for 15 seconds.
4. Now click on " Jailbreak . "
5. Restarts, loading the new application "Loader" from "Greenpois0n" and install "Cydia".
6. With "Cydia" installed, you can now remove the application "Loader".
7. Ok, now you have your device with Jailbreak . 

Here are the video demonstration of how to perform these steps.