1. Notification Center
Apple has created a very beautiful version of third party notification app Growl. When new messages come through in iMessage, Mail, Twitter and other supported apps, a message will discreetly alert you of the new information without you having to leave the screen you're on by presenting a small pop-up notification.
From wheelchair accessibility in Apple retail stores to access to technology and the Internet, Steve Jobs has always taken inclusion of any type of user very seriously. Apple had text-to-speech software built-into its native OS before any of the other major players. With Mountain Lion, you can dictate text into any field. It will even work in applications like Microsoft Word.
The box with an arrow coming out of it that any iOS user is familiar with now comes to Mac apps. You can now share to a variety of locations between both apps and different social networks such as Flickr, Twitter, Message and Email.
4. Power Nap
Ever wished that your computer would simply take a nap instead of going completely to sleep? Now you can set up Power Nap to automatically backup and refresh your data so that when you are ready to come back to your machine, everything is backed up and all the information is updated and ready to go.
5. Airplay Mirroring
You will finally be able to share your screen to your Apple TV wirelessly.
6. Game Center
Take your bragging rights everywhere with your iPhone, iPad and now your computer with Game Center. Never lose out on a badge or a documented high score again.
7. Search in Launchpad
Too many free apps from the app store filling up your Launchpad screen? Now you can search for that specific app in Launchpad. Since it only sorts the search by the name of the app, it's a more efficient search than the Spotlight search.
8. Offline Reading List
See a long-form article in Safari that you simply don't have time to read and appreciate? Save it for Offline Reading so that you can access it anytime, anywhere.