Apple has released iOS 4.3.4 for iPhone 4, 3GS, iPod Touch 4, 3G, iPad 1 and iPad 2, along with iOS 4.2.9 for Verizon iPhone 4 that includes fix for PDF vulnerability which is used by Comex in JailbreakMe 3.0.
Warning: Users who rely on unlock or jailbreak must stay away from these iOS updates.
Download iOS 4.2.9 for iPhone 4 (CDMA)
Download iOS 4.3.4
iOS 4.3.4 for iPhone
iOS 4.3.4 for iPod Touch
iOS 4.3.4 for iPad