If you are an iPhone owner, you'll probably want to read this:

Last night JailbreakMe was released in the wild. As we reported, it's one of the simplest jailbreak tools ever made, as it requires only one slide in Mobile Safari to install Cydia on your device. You visit a link, slide, and wait. As we also reported, though, the exploit seems to based on a PDF vulnerability in iOS: the iPhone automatically downloads PDF files, and Comex injected the jailbreak code in a PDF file.