Apple today released a developer preview of OS X Mountain Lion, the ninth major release of the world’s most advanced operating system, which brings popular apps and features from iPad to the Mac and accelerates the pace of OS X innovation. 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 the first OS X release built with iCloud in mind for easy setup and integration with apps. The developer preview of Mountain Lion also introduces Gatekeeper, a revolutionary security feature that helps keep you safe from malicious software by giving you complete control over what apps are installed on your Mac. The preview release of Mountain Lion is available to Mac Developer Program members starting today. Mac users will be able to upgrade to Mountain Lion from the Mac App Store in late summer 2012.