Today, Apple released the iOS 4.0.2 update for iPhone. This patch fixes the PDF exploit that allowed recent web-based JailBreakMe, the first jailbreak for iOS 4 and the iPhone 4. Jailbreaking is a process that unlocks the operating system and allows users to download many apps, extensions and themes unavailable through the App Store. It’s a recommended OS update for users — unless your iPhone is jailbroken.

iOS 4.0.2 install for iPhone

If your iPhone is not jailbroken, this is an essential OS update to apply. Although it adds no new features or functionality to the iPhone, the 4.0.2 update patches a security hole that could could be used by hackers to gain remote control of your iPhone simply by directing unsuspecting users to a website in Mobile Safari. To update your iPhone’s OS, just sync your iPhone with iTunes and let it do its magic. When it asks you to update the operating system, click yes.

If you’ve jailbroken your iPhone using the JailBreakMe website, this OS update will break the jailbreak and you probably shouldn’t update at this time. If you haven’t already, save your SHSH (Cydia should have instructions), and wait until the next jailbreak. Or if you can tolerate iTunes nagging you every time you sync your iPhone, just hold off on this update. It adds no other new features or functionality.

It looks like iPhone 2G and iPod 1G owners who took advantage of this particular jailbreak get to keep it. This patch is iOS 4 only and Apple has no current plans to update iPhone OS 3 to fix the Safari exploit.

Warning: Jailbreaking your iPhone will void its warranty. It can cause other problems as well. Jailbreak at your own risk.