Mountain Lion includes a set of 44 beautiful screensaver images in stunning 3200×2000 resolution, ideal for use as wallpaper on Retina MacBook Pros, Thunderbolt Displays and larger Cinema Displays.
Getting access to the images to use as wallpaper takes just a few seconds. Instructions follow…
In the Finder, from the Go menu select Go to folder… (or hit CMD-Shift-G).
In the box that opens up, paste in this:
That will open up the folder where the screensaver images are stored. Hit CMD-A to select all of them, then CMD-C to copy. Now open or create the folder where you’d like to store the wallpaper and hit CMD-V to paste in the copies.
Then simply right-click the photo you’d like to use as your wallpaper and select Set Desktop Picture.