Apple’s Developer Center just updated with the new Mountain Lion resources only available to registered Mac developers. Most importantly: Those with a paid developer account can now immediately download OS X Mountain Lion Developer Preview. The software delivers through the Mac App Store and it replaces your previous operating system version, so make sure to use it on a test machine and not your primary productivity system. Just log in to your developer account, access the Mac section, click the OS X Mountain Lion tab, and then hit the Get Redemption Code button next to the OS X Mountain Lion Developer Preview or OS X Mountain Lion Server Developer Preview. This will launch the Mac App Store and start the download process. You must use a 64-bit, Intel-based Mac running either Mac OS X v10.6.7 Snow Leopard or OS X Lion and have at least 8GB of free disk space to install the OS.
In addition to the pre-release version of the operating system, Apple also made a number of related resources available, including guidelines for developing apps for Mountain Lion, GameKit, and GLKit programming guides that explain how to write Game Center-compatible games using social gaming and graphics technologies that debuted in iOS 5 and more. Finally, following a brief removal of Xcode 4.3 from the Mac App Store this morning, the new Xcode 4.4 Developer Preview for OS X Mountain Lion is now available in your dev account and it includes the Mac OS X 10.8 SDK and iOS 5 SDK.