Apple has released iOS 4.0. Head over to iTunes for the upgrade. Please ensure you have the latest iTunes 9.2. iOS 4.0 is compatible with iPhone 3G, iPhone 3GS, 2G iPod touch and 3G iPod touch. First generation iPhone and iPod touch are not supported. Certain [iOS 4.0 features such as multitasking, custom wallpaper etc](http://sanziro.com/2010/06/ios-4-missing-features-in-iphone-3g-and-second-generation-ipod-touch.html) are not supported on iPhone 3G and 2G iPod touch.