One of the things Mountain Lion brings back to the Mac is the "Save As..." command, but it is not immediately apparent if you don't know where to look. To make that menu choice appear miraculously go to the "File" menu of an app that uses a typical "Save" command, and while choosing it hold down the "option" key on your keyboard. You will see the "Duplicate" menu choice be replaced by the "Save As..." menu choice instead.
