Step One
Press to launch Safari from your Springboard.
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Step Two
Press to select the address bar and input http://jailbreakme.com then press the Done button.
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Step Three
To begin the jailbreak simply move the slider to right.
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Step Four
You will be displayed a status bar as the download progresses.
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Step Five
Once the download is complete the jailbreak process will begin
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Step Six
Once you are notified that the jailbreak process is complete press the OK button.
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Press the Home button to reveal Cydia on your desktop!
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Congratulations you are done! You may now continue by installing UltraSn0w to unlock you device. iPhone 4 users still need to wait a bit for an UltraSn0w update which will arrive shortly.
A big thanks goes to Comex and the iPhone Dev-Team for their efforts and successes.