The Displays preference has changed a bit, with the best feature being the addition of the AirPlay mirroring feature.
If you have an Apple TV then you can mirror your Mac’s Desktop to your TV screen, which is great for simplifying presentations.
You could have an Apple TV hooked up to a Projector or a Large Screen TV, and have people wirelessly connect to them, preventing the messing around with VGA Cables or forgotten adapters.
A brand new System Preference for 10.8 is the Notifications Preference.
This is essentially just the same as the one on iOS, and gives you options over what type of alerts you receive from all of the various applications on your Mac
Usually the default options for each app are fine, the one thing I would recommend doing however is re-arranging the list so that the apps important to you are at the top of the Notification Center
If you haven’t discovered the Notification Center yet, its accessed by clicking on the notification icon in the menu bar, the 3 dots and 3 lines in the very top right hand corner.
If you have set up your Facebook account, then you will also have a box at the top of this to post instantly to Facebook.
It appears that originally, Zip files had a 4GB limit, and the software that is part of the Mac OS is only able to open files under this size
If you have zip archives over 4GB then you will need software capable of extracting this, thankfully there is The Unarchiver, a free app from http://wakaba.c3.cx/s/apps/unarchiver.html
Download and install the App into Applications by dragging it there
For ease of use I will put the icon in the dock, then you can just drag a zip archive to the icon to begin extraction