The iPhone shows just how much simpler the concept of app installation — and just as importantly, un-installation — can be. There is only one place where iPhone apps can be: on one of the home screens. The entire file system has been abstracted away. If you see the app icon, it is installed. If you want to get rid of it, you just press and hold to invoke jiggle mode and tap that icon’s X button. Even better, there is nothing to “clean up” after an iPhone installation: no mounted image to unmount, no .zip or .dmg download file to throw away.
— Daring Fireball: How Should Mac Apps Be Distributed?
