The company broke the during the opening keynote at the , which kicked off on Monday in San Francisco.
Craig Federighi, the company's top OS X executive, spelled out some of the more than 200 new features in Mountain Lion, ranging from several new applications, including Notes and Reminders, both borrowed from iOS, to Power Nap, which allows some notebooks to conduct backups and receive software updates while in sleep mode.
Apple will launch the upgrade some time next month, said Federighi, although he did not specify a date.
But the company may be on the same schedule it used last year for OS X 10.7, or Lion.
As it did for that 2011 upgrade, Apple today issued a fourth developer preview for Mountain Lion, and Federighi said it was in "nearly finished" shape.