Apple just released a developer preview of OS X Mountain Lion, which is the ninth major release of the operating system, which brings popular apps and features from... iPad to the Mac and accelerates the whole system. Mountain Lion introduces Messages, Notes, Reminders and Game Center to the Mac, as well as Notification Center, Share Sheets, Twitter integration and AirPlay Mirroring. Mountain Lion is also built with iCloud in mind for easy setup and integration with apps. The developer preview of Mountain Lion also introduces Gatekeeper, a security feature that helps keep the computer safe from malicious software. The preview release of Mountain Lion is available to Mac Developer Program members. Mac users will be able to upgrade to Mountain Lion from the Mac App Store in late summer 2012.

“The Mac is on a roll, growing faster than the PC for 23 straight quarters, and with Mountain Lion things get even better,” said Philip Schiller, Apple’s senior vice president of Worldwide Marketing. “The developer preview of Mountain Lion comes just seven months after the incredibly successful release of Lion and sets a rapid pace of development for the world’s most advanced personal computer operating system.”

Starting today Lion users can also download a beta of Messages communicator from Apple's website, and the final version will be available with Mountain Lion.

Apple reports that more than 100 million users have iCloud accounts, and Mountain Lion makes it easier than ever to set up iCloud and access documents across devices. "Mountain Lion uses your Apple ID to automatically set up Contacts, Mail, Calendar, Messages, FaceTime® and Find My Mac. The new iCloud Documents pushes any changes to all your devices so documents are always up to date, and a new API helps developers make document-based apps work with iCloud."

Hundreds of new APIs give developers access to new core technologies and enhanced features within OS X. The Game Kit APIs tap into the same services as Game Center on iOS, making it possible to create multiplayer games that work across Mac, iPhone, iPad and iPod touch. A new graphics infrastructure underpins OpenGL and OpenCL and implements GLKit, first introduced in iOS 5, to make it easier to create OpenGL apps.

Source: http://www.apple.com