Apple’s software upgrade to iOS 4 is out today. Here’s what Apple says about compatibility:
iOS 4 works with iPhone 4, iPhone 3GS, and iPhone 3G. Not all features are compatible with all devices. For example, multitasking is available only with iPhone 4 and iPhone 3GS.
It also works with second and third-generation iPod touch devices.
iOS 4 adds a range of new features, including multi-tasking (not for all devices), digital camera zoom, email improvements, folders and bluetooth keyboard support:
