iPhone's security rivals Windows 95 (no, that's not good).

"It wasn't long after Apple released the iPhone in June that researchers discovered that every application on the device -- from the calculator on up -- runs as 'root,' i.e., with full system privileges. As a result, a serious vulnerability in any of these applications would allow hackers to gain complete control of the device... Miller says that Apple will need to redesign the entire firmware to fix the problem -- which would require owners to install a pretty hefty update."