Apple has released the latest update to iOS, now version 4.3.5, to address security flaws. This update comes quickly after the 4.3.4 update which addressed a similar security flaw used to jailbreak iDevices. Users should download the update via iTunes when their iPhone, iPad, or iPod touch is plugged into their computer.
From the Apple knowledge base article about the update:
"Available for: iOS 3.0 through 4.3.4 for iPhone 3GS and iPhone 4 (GSM), iOS 3.1 through 4.3.4 for iPod touch (3rd generation) and later, iOS 3.2 through … Read more