Apple has announced that OS X Mountain Lion, the ninth major release of Mac OS X, is available as a download from the Mac App Store.

It boasts more than 200 new features, Mountain Lion includes iCloud integration, the all new Messages app, Notification Center, systemwide Sharing, Facebook integration, Dictation, AirPlay Mirroring and Game Center. Well, actually, Facebook integration will be available in an upcoming software update to Mountain Lion.

OS X Mountain Lion is available from the Mac App Store for US$19.99. It requires Lion or Snow Leopard (OS X 10.6.8 or later), 2GB of memory and 8GB of available space. For a complete list of system requirements and compatible systems, go to apple.com/osx/specs.

OS X Server, also available today, requires Mountain Lion and is available from the Mac App Store for $19.99. The OS X Mountain Lion Up-to-Date upgrade is available at no additional charge from the Mac App Store to all customers who purchased a qualifying new Mac system from Apple or an Apple Authorized Reseller on or after June 11, 2012.