"Look ma, no images!"
Well, that's not entirely true: The Apple logo and the magnifier are images, but everything else (shadows, gradients etc.) has been created using only CSS(3). Pretty cool, don't you think? You'll even see an animation of the menu, when viewing this page using a Webkit browser (Safari or Chrome).
This menu is a clone of the current top menu of the Apple.com website (without the animations/effects etc. of the search navigation). Dive into the source code of this page to find out how it's created.