JailbreakMe.com is a website that offers visitors the ability to jailbreak their iPhone without a computer-based tether. It does this by exploiting the system-wide ability for applications to read PDF files, where an incorrectly-formatted PDF file can lead a hacker to do anything they want to your system. While this bug CAN be used maliciously to steal all the personal data from your phone, the developers in this instance used it to enable jailbreaking.
Others will tell you why you should or should not jailbreak your iPhone. Others will decry the developers for bringing to light a serious vulnerability in the iPhone OS. In this blog post, I won’t do any of that, but will instead point out some things you should and shouldn’t do if you decide to jailbreak.