Apple has recently launched Developer Preview of its new upcoming operating system "OS X Mountain Lion". The os is currently launched on for testers and Developer for testing purpose, so that they can report/fix as many bugs as they can before the final release of the OS in coming summer.

One iCloud:
We all know Apple’s iCloud technology is best in syncing music, photos along with data among iOS Devices and to a limited extent Macs. Now it will be more convenient as In OS X Mountain Lion, you just need to sign in once with your Apple ID and iCloud is automatically set up across your Mac computer.


New “Messages” Instead of “iChat” :
As Apple has removed the difference between Mac and iOS devices (introduced Mountain Lion same as iOS), they have replaced the iChat software with the new ‘Messages’.It is very similar to iMessage in iOS, users can send unlimited messages to anyone on a Mac or an iPhone, iPad, or iPod touch running iOS 5. It allows us to easily send photos and videos via messages, and we can also launch FaceTime from the app as well.


Reminders:
iOS 5 users know about this very well. When you have so much to do, it allows you make a lists within tasks, and you can set alerts. It’s all in a list. Set due dates and you’ll get alerts as deadlines approach. Check items off your lists as you go and keep track of what you’ve completed.


Notes:
This is also the one came from iOS 5, but with few special features. Now you can make it more significant with photos, images, and attachments. We can also make them like Post-It notes, sticking individual notes on the home screen to make always appear "on top" of your apps. Notes works with iCloud, so when you create or edit a note on your Mac, it automatically updates on your iPhone, iPad, and iPod touch.


Notification Center:
No matter an email, an instant message, a friend request, a calendar alert, or anything…you are not going to miss anything. Notifications keep poping up anywhere on your MT LION system. But you can select which notifications you want to see in Notification Center and place them according to you like. Just scrolling your fingers on your trackpad will open up your notifications list on the right side of the screen.


Fastest Share Sheets:
This is something new. It is an added button to all apps that allows you to share anything right away. It’s the new, easy way to spread the word — links, photos, and videos, too. When You can quickly send a link from Safari browser or share a photo directly from iPhoto or Photo Booth. Also send your notes via Mail and Messages.


Twitter tweets anytime:
Similar to Share Sheet, Twitter is also now integrated with new Mountain Lion. You just need to Log in once from you System Preferences enables sharing across all apps. Tweet links and photos directly from Safari, iPhoto, or Photo Booth with the new Tweet Sheet. Tweet comments and add locations.


Game Center:
Many iOS users also love playing games on their iPhone, iPad or iPod Touch. Now the same iOS Game Center comes to Mac systems with the new Mountain Lion. Now it’s a bigger playing field with even more competition. Just create a Game Center account with your Apple ID. Then sign in and you’re in. One better feature of this is that with Mountain Lion you'll be able to play games on your Mac online with your colleagues using iOS devices.


AirPlay Mirroring:
With the new Airplay Mirroring you can stream music and videos wirelessly to any AirPlay-compatible device, which includes Apple TV. Show web pages and videos to friends on the couch. Share lessons with a classroom. Present to a conference room, and lots more.



Gatekeeper:
Gatekeeper included in new Mountain Lion to keep your Mac safer than ever before. It protects you from mistakenly downloading and installing malicious applications. You can choose your own System Prefs the level of protection you want. Now you can choose from three security options. You can download and run applications from anywhere, just as in OS X Lion. To be even safer, download and run apps from the Mac App Store and apps with a Developer ID. Or download and run only apps from the Mac App Store — the safest setting of all.


China and Chinese:
Many Apple services like Mail, Contacts and Calendar now work with top Chinese online services, for example Baidu. And now OS X Mountain Lion brings all-new support for a lot of well-known Chinese services.Now we will get Baidu as a built-in option in Safari browser. The video-sharing websites like Youku and Tudou are also integrated in the new Share Sheets that will help Chinese users to post videos to the web easily. They can also blog with Sina weibo, the popular microblogging service. And with enhanced text input, typing in Chinese is easier, faster, and more perfect.