Mountain Lion's new features

With Mountain Lion, Apple replaces the iChat instant messaging application with Messages, which supports Apple’s iMessage chat system. You can use iMessage from your Mac to chat with friends and family on an iPhone or iPad, and since it uses the Internet and not cellular service, iOS device user won’t incur any per-message charges.

Read our hands-on with Messages.

Messages has a revamped user interface, with a list of conversations on the left, and the main chat window on the right. Messages still has support for AIM, Yahoo, and Jabber protocols, so you can still IM with folks who aren’t on a Mac or iOS device. Apple is offering a public beta of Messages, which requires OS X 10.7.3 or later.

You can also read our hands-on with Messages before trying the beta.

The new Notes app in Mountain Lion features the familiar yellow pad that iOS users recognize. Notes uses iCloud to sync between your Mac, iPhone, iPad, and iPod touch. Double-click on a note, and it appears in its own window, a la Stickies.

Learn more about Notes.

Taking over the far right corner of the menu bar is the Notification Center icon (Spotlight moves over to the left one spot). Click on it, and a list of recent notifications appears on the right side of the screen. If you have a trackpad, you can this list by performing a two-finger swipe starting at the trackpad’s right edge.

Find out more about Notification Center.

A new Notifications system preference will allow you to adjust how alerts appear. Currently, only Apple apps are supported, but third-party developers will be able to take advantage of this feature.

Find out more about Notification Center.

Like Notes, Reminders uses iCloud to sync between the Mac and iOS devices. Mountain Lion Reminders is missing features that are found in iOS Reminders, such as location-based reminders.

Learn more about Reminders.

When you want to send a Web article to someone, share photos, send notes, or post a link to Twitter, you can do so using Share Sheets. The Share Sheets icon looks just like the one in iOS. This picture shows the Share Sheets button in Safari.

Get more details on Share Sheets.

iCloud is key to Apple’s products, and Mountain Lion has more integration with the online data sync service. You’ll be asked to enter an Apple ID during the OS installation, so your settings and data can be synced. Mountain Lion also has a new Documents in the Cloud view to go along with the Open and Save dialog boxes.

This new feature allows you to control the kind of apps your Mac can run. You can choose to run only software bought through the Mac App Store, or run both Mac App Store software and programs from identified developers (third-party apps that weren’t bought through the Mac App Store but are registered with Apple). Or you can allow any app to run, regardless of its origin.

Find out how Gatekeeper works.

AirPlay Mirroring was introduced with iOS 5. It allows an iPhone 4S or iPad 2 to connect to a second-generation Apple TV in order to display what is on the iOS device’s screen. With Mountain Lion AirPlay mirroring, a 720p video stream of your Mac’s screen is sent to the Apple TV, which then displays the video on an HDTV.

In addition to the Share Sheet button, Safari now has a unified search and address bar. URLs are also displayed differently; the domain name is displayed in black, while the rest of a URL is in gray.

Got a game that’s available on both iOS and the Mac? Mountain Lion’s Game Center allows you to play against other people, regardless of the platform. Game Center features also include in-game chat, opponent matching, and more.

Mountain Lion has better support for the growing Chinese market. The Baidu search engine is an option in Safari, and the Twitter-like service called Sina Weibo is an option in Share Sheets. Other Chinese services are available throughout Mountain Lion’s settings. Apple has also expanded its support for Chinese text input.