The Wayback Machine - https://web.archive.org/web/20120731224425/http://www.apple.com/osx/whats-new/

Reminders. Now nothing slips your mind.

Organize your life on your Mac. It’s all in a list. More than one, in fact. Make as many lists as you need and easily add to them. Set due dates and you’ll get alerts as deadlines approach. Set a location from your Mac, and your iPhone or iPad will remind you when you get there.2 Check items off your lists as you go and keep track of what you’ve completed. iCloud keeps your reminders up to date on your Mac, iPad, iPhone, and iPod touch, so you don't forget anything.

Notes. Not one thought lost.

Notes is designed for whatever’s on your mind, wherever you happen to be. Think it up. Jot it down. Make it even more noteworthy with photos, images, and attachments. You can add, delete, and flip through your notes or do a quick search. Use the Share button to send your notes with Mail or Messages. Pin important notes to your desktop so they’re easy to get to. And take them with you everywhere. 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. And vice versa.

Power Nap. Mac stays up to date, even while it sleeps.

When your Mac goes to sleep, it still gets things done with Power Nap.3 It periodically updates Mail, Contacts, Calendar, Reminders, Notes, Photo Stream, Find My Mac, and Documents in the Cloud. When your Mac is connected to a power source, it downloads software updates and makes backups with Time Machine. While all that updating is going on, the system sounds are silent and no lights or fans come on, so nothing disturbs you. And when your Mac wakes up, it’s good to go.

Dictation. Talking is the new typing.

Now you can talk anywhere you can type. Dictation converts your words into text. It uses the built-in microphone on your Mac, so there’s no need to set anything up — just start speaking instead of typing. When you say “comma” or “exclamation point,” Dictation punctuates for you. The more you use Dictation, the smarter it gets. It learns voice characteristics. And it recognizes people from your contacts so it enters names accurately. Dictation supports English (U.S., UK, and Australia), French, German, and Japanese.

Sharing. Share right from here.

You’ll find the Share button throughout OS X Mountain Lion. It’s the new, easy way to share right from the app you’re using. Share photos, videos, and other files with Mail, Messages, and AirDrop. Send links from Safari. And with a few clicks, post straight to Facebook,4 Twitter, Flickr, or Vimeo when the moment strikes.

Twitter. Tweet right from your apps.

OS X Mountain Lion is designed for tweeting. Sign in once and you’re all set up — and you don’t have to leave the app you’re in. Tweet links and photos directly from Safari, iPhoto, or Photo Booth with the new Tweet sheet. Add comments and locations. And when someone mentions you in a tweet or sends you a direct message, you’ll get a notification right then and there. You can tweet from Notification Center, too.

AirPlay. Your Mac is on TV.

AirPlay Mirroring is made for an audience. Because with a click, what’s on your Mac is also on your HDTV. It’s easy to set up with Apple TV. Show web pages and videos to friends on the couch, share lessons with a classroom, or present to a conference room. AirPlay audio streams the music, podcasts, and other audio on your Mac to AirPlay-enabled speakers. It’s a big deal for your Mac. And for everyone around it.

Gatekeeper. Downloading apps is safer than ever.

Gatekeeper helps protect you from downloading and installing malicious software on your Mac, no matter where your apps come from. And it gives you even more control over which apps you install. You can download and install apps from anywhere on the web, just as you always could. You can choose to download and install apps from the Mac App Store — the safest place to find apps for your Mac. Or use the Gatekeeper default option, which allows you to install apps from the Mac App Store and apps from identified developers. It’s a new way OS X keeps your Mac safe. Learn more about Gatekeeper and other security features

All-new features for China.

OS X Mountain Lion brings all-new support for many popular Chinese features and services. The dictionary app now includes the Standard Dictionary of Contemporary Chinese. Improved text input makes typing in Chinese easier, faster, and more accurate. With eight new fonts, your writing can appear formal, informal, or fun. Mail works with QQ, 163, and 126. Baidu, the leading Chinese search provider, is a built-in option in Safari. Now you can post to the web right from the app you’re in. Post videos with Youku and Tudou. Post to Sina Weibo, the popular microblogging service. And share easier than ever. All these new services are easy to set up on your Mac.

  1. iCloud requires iOS 5 on iPhone 3GS or later, iPod touch (3rd and 4th generation), or iPad; a Mac computer with OS X Lion or later; or a PC with Windows Vista or Windows 7 (Outlook 2007 or 2010 or an up-to-date browser is required for accessing email, contacts, and calendars). Some features require a Wi-Fi connection. Some features are not available in all countries. Access to some services is limited to 10 devices.
  2. Location-based reminders on iPad requires iOS 6.
  3. Power Nap requires a Mac notebook with built-in flash storage. May require a firmware update.
  4. Facebook integration coming this fall.
  5. Game Center is available on iPad, iPhone 3GS or later, iPod touch (3rd generation and later), and Mac computers with OS X Mountain Lion. Game Center works with games that have been developed to work with the Game Center service. Game Center may not be available in all countries or regions, and the available games may vary by country or region.
  6. iCloud Tabs on iPhone, iPad, and iPod touch requires iOS 6.
  7. Testing conducted by Apple in July 2012 using SunSpider 0.9.1 JavaScript performance benchmark on a 21.5-inch iMac 2.7GHz Intel Core i5 system with 4GB of RAM. Safari 6.0, Chrome 20.0.1132.47, and Firefox 13.0.1 tested on OS X v10.8. Internet Explorer 9.0.8112.16421 tested on Windows 7 Ultimate SP1 (64-bit). Performance will vary based on system configuration, network connection, and other factors.