Today, Apple announced on their iOS Developer blog that apps targeting to iOS 2.x will no longer be supported. This is no surprise as we are already at iOS 4. Developers are encouraged to re-build their apps in Xcode and set the target to iOS 3.x or later so they will not run into submission or app removal issues.
Apple also recommends that developers review the iOS 4 Readiness Checklist in order to take full advantage of the bevy of new technologies and API’s available in the latest iOS release.
iOS 4 is now available as a free update for iPhone 3G, iPhone 3GS, and the 2nd and 3rd generation iPod touch. iOS 4 only runs to its full potential, with multitasking, on iPhone 3GS, iPhone 4, and the 3rd generation iPod touch.