After releasing iOS 4.2.1 for all iOS devices (iOS 4.2 for Apple TV 2G), Apple has pushed official iOS 4.2 final SDK to the developers. Apple has also introduced the set of Application Tools which can be used to submit apps to the Mac App Store.
Xcode and iOS SDK 4.2
This is the complete Xcode developer toolset for Mac, iPhone, and iPad. It includes the Xcode IDE, iOS Simulator, and all required tools and frameworks for building Mac OS X and iOS apps.
For those who don't know, iOS 4.2 (4.2.1) comes with a huge number of new features including AirPrint, AirPlay, Multitasking, Folders and a free Find My iPhone service for iPhone 4, iPod Touch 4G and iPad users. Apparently iOS 4.2.1 has no performance or speed issues for iPhone 3G.
Note that unlike beta releases, iOS 4.2 SDK can be downloaded by any registered developer without paying $99 yearly membership fee. Just login here and grab iOS 4.2 SDK final bits from Apple Developer Center.Contact Us for News Tips, Corrections and Feedback