Despite the fact that Apple just released OS X Lion less than a year ago (seven months, if you were looking for a more precise period of time), the company has been hard at work on the next build of Mac OS X and today released a preview of OS X Mountain Lion for developers. This version of OS X drops the 'Mac' from the title, which is the first big hint at where Apple is headed with its desktop OS. Mountain Lion further bridges the gap between Cupertino's mobile and desktop computers with more than a hint of iOS appearing in this latest version.
Apple started mixing iOS with Mac OS X with Lion and that's continuing through with Mountain Lion. The most notable example of this is the presence of iOS features such as Game Center, Notifications, and iMessage (which arrives in the form of an iChat revamp called Messages). Notifications is something that Growl-lovers will recognize, and provides users with alerts from every corner of their Mac, from system updates to Messages to third party applications. Messages is the newest version of Apple's iChat app and supports iMessage. It also pools IM, text messaging, and message history into a brand new interface, though, so while it is technically an updated iChat, it looks completely different.
AirPlay Mirroring is another major feature of OS X Mountain Lion, and, again, it should be very familiar to iOS users already making use of AirPlay. This feature will allow you to mirror what’s on your Mac's display and send it over to your HDTV via Apple TV. Supporting up to 720p, AirPlay Mirroring means you can watch movies or TV shows and play games without that cramped feeling that comes with performing such activities on a computer. It's worth noting that Apple has said AirPlay Mirroring will only work for Macs with second-generation Intel Core processors.
Apple is also taking OS X to the iCloud with this build. Mountain Lion will use your Apple ID to automatically set up Contacts, Mail, Calendar, Messages, FaceTime and Find My Mac. These will continuously sync across all of your Apple devices and is the reason Messages, for example, will be able to show you a combined history of IM, SMS, and message history for each of your contacts. There's also a new API for developers to make document-based apps work with iCloud.
Lastly, there's Gatekeeper, which is a security setting that allows you to set your computer so that it will only accept software downloaded from the Mac App Store, or from the Mac App Store and identified developers. This setting can also be switched off completely, allowing you to download applications from anywhere. In case you were wondering, an identified developer is a developer that has signed their apps prior to distribution. Apple says Gatekeeper's default setting will be for Mac App Store apps and apps by identified developers only. This security setting will probably be the most useful for people sharing a computer with (or setting up a new computer for) less tech savvy people.
Mountain Lion has over 100 new features, and these are just a handful of them. If you're eager to know more, the OS has been released as a developer preview, so you can check it out for yourself. If that doesn't interest you, Engadget has a great in-depth preview of Mountain Lion. OS X Mountain Lion is scheduled for release this summer.