How To: Jailbreak iPhone 4, 3GS, iPod touch 4G, 3G, 2G on iOS 4.1 with Greenpois0n on Mac OS X

[SOURCE: Covering Web]

STEP 1: Download Greenpois0n jailbreak (link at the end)
STEP 2: Connect your iPhone/iPod to your computer via USB then launch Greenpois0n jailbreak application and hit "Jailbreak" button. 

STEP 3: Follow the steps shown on the next screen shots to put your device in DFU mode.

• Now you have to press and hold the sleep button for 3 seconds.

• Continue holding sleep, then press and hold home for 10 seconds.

• Now release sleep button but keep holding home for 15 seconds.

STEP 4: Once your iPhone/iPod is in DFU mode, the jailbreak will begin.

STEP 5: Now press "Complete" button.

STEP 6: Restart your iPhone, now you will notice Loader application icon on your springboard, hit this icon.

STEP 7: Now press "Cydia", then "Install Cydia". After finishing you will be asked to remove Loader from your device, click "Remove", then press Home button, the device will restart automatically.

 

 

 

STEP 8: After your device restart you will find the Cydia icon, Congratulations. 

Note: Since there is no way to unlock 05.14.02 / 2.10.04 basebands, you should upgrade to iOS 4.1 with preserving your baseband before using Greenpois0n jailbreak by following our guide (for iPhone 4 ONLY) posted here.

Download iOS 4.1 for iPhone 4/3GS. 
Download Greenpois0n jailbreak for iOS 4.1.