Apple has released Mac OS X Mountain Lion Developer Preview, signalling the beginning of the public testing phase of its next-generation desktop operating system.

According to Apple, the Mountain Lion Developer Preview brings more than 100 new features to Mac OS X, including Messages, Notes, Reminders and Game Center to the Mac, as well as Notification Center, Share Sheets, Twitter integration and AirPlay Mirroring.

First Look: Mac OS X Mountain Lion

“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.”

The preview release of Mountain Lion is available to Mac Developer Program members starting from today. The full version of Mountain Lion will be available from the Mac App Store in late summer 2012, Apple said.

The ninth iteration of Mac OS X, codenamed Mountain Lion, continues with Apple's big cat-themed name that it has used for OS X versions since 10.2, which was known as Jaguar. Versions 10.0 and 10.1 (Cheetah and Puma, respectively) did have big cat-related codenames, but these terms were only ever used internally.

Interestingly, the Mountain Lion is native to Apple's home state of California, and is also known as a Cougar. This term, however, may have been rejected after becoming part of the lexicon as a term used to describe a sexually predatory older female.