Mountain Lion will sell for $19.99 for existing OS X Lion and Snow Leopard users.
Revealed by Apple today at its Worldwide Developers Conference in San Francisco, the new version of OS X will start shipping in July. The new OS will be available in Apple's Mac App store.
Apple's newest operating system builds in several features inspired by its iOS mobile devices. Apple SVP Craig Federighi, who showed off the system, said the new OS has more than 200 new features, including notifications, Reminders, Game Center, Documents in the Cloud, and Messages.
Many of these features are standalone programs, but some, such as the Notification Center and sharing tools, are systemwide services. Apple is also enhancing security options with a service that warns you when you could potentially download harmful software.
Federighi demoed the Reminders app and Notes app, both with dedicated icons on the Dock. He showed off the Messages app and demonstrated the drag-and-drop functionality of Documents in the Cloud.
Another new feature, called, is all about keeping Macs up to date even while they're snoozing. The computers will be able to fetch data while in sleep mode, do an iCloud sync, update system software, get e-mail, and even do a Time Machine backup.