Apple took the opportunity at today's WWDC keynote to demonstrate ten new Leopard features. The highly-anticipated OS upgrade comes after the runaway success of OS X Tiger, with two-thirds of machines running that system. Apparently Leopard will introduce more than 300 new features. First off, Jobs showed the new Leopard desktop with a narrower dock and it and the menu bar being transparent. Desktop stacks are newly tidied, either fanning out from the dock or popping up in a grid; there's a default stack called "downloads" which sticks in place. Each new document defaults to the front of the stack, and you can put applications there too and use stacks as an app-launcher.