Apple today launched OS X Mountain Lion, the ninth version of the 11-year-old Mac operating system. As promised yesterday by the company's chief financial officer, Mac OS X 10.8, aka Mountain Lion, is available as a download from the Mac App Store.

According to Apple, the OS features more than 200 new features, includes iCloud integration, the all new Messages app, Notification Center, system-wide Sharing, Facebook integration (available in an upcoming software update), Dictation, AirPlay Mirroring and Game Center. Mountain Lion is also available as an upgrade from Lion or Snow Leopard for $19.99.

Specifically, Mountain Lion includes:

- iCloud integration, for easy set up of your Mail, Contacts, Calendar, Messages, Reminders and Notes, and keeping everything, including iWork documents, up to date across all your devices;

- the new Messages app, which replaces iChat and brings iMessage to the Mac, so you can send messages to anyone with an iPhone, iPad, iPod touch or another Mac;

- Notification Center, which streamlines the presentation of notifications and provides easy access to alerts from Mail, Calendar, Messages, Reminders, system updates and third party apps;

- system-wide Sharing, to make it easy to share links, photos, videos and other files without having to switch to another app, and you just need to sign in once to use third-party services like Facebook, Twitter, Flickr and Vimeo;

- Facebook integration, so you can post photos, links and comments with locations right from your apps, automatically add your Facebook friends to your Contacts, and even update your Facebook status from within Notification Center;

- Dictation, which allows you to dictate text anywhere you can type, whether you?re using an app from Apple or a third party developer;

- AirPlay Mirroring, an easy way to wirelessly send an up-to-1080p secure stream of what?s on your Mac to an HDTV using Apple TV, or send audio to a receiver or speakers that use AirPlay; and

- Game Center, which brings the popular social gaming network from iOS to the Mac so you can enjoy live, multiplayer games with friends whether they're on a Mac, iPhone, iPad or iPod touch.

Additional features in Mountain Lion include the new Gatekeeper, which makes downloading software from the Internet safer; Power Nap, which automatically updates your apps and system while your Mac is asleep; and a faster Safari browser. New features for China include significantly improved text input, a new Chinese Dictionary, easy setup with popular email providers, Baidu search in Safari, and built-in sharing to Sina Weibo and popular video websites Youku and Tudou.

OS X Mountain Lion is available from the Mac App Store for $19.99 (US). Mountain Lion requires Lion or Snow Leopard (OS X v10.6.8 or later), 2GB of memory and 8GB of available space.

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

Apple's rival Microsoft is also upgrading Windows this year, and like Apple, has reduced the price. An upgrade to Windows 8 Pro will sell for $39.99, or 20% less than the lowest price for Windows 7 three years. Windows 8 ships Oct. 26.