Apple Sells Two Million Copies of Mac OS X Leopard in First Weekend  —  Apple® today announced that it sold (or delivered in the case of maintenance agreements) over two million copies of Mac OS® X Leopard since its release on Friday, far outpacing the first-weekend sales of Mac OS X Tiger …

Source:   Apple

Link:   http://www.apple.com/pr/library/2007/10/30macosx.html