CSS is used to create the drop down menus. The top menu does not work correctly with Internet Explorer as it's CSS model has not got as far as implementing pseudoclasses for any object other than the anchor. The left menu uses JavaScript which results in the interesting way you can pin up the submenus but only one at a time.
Lists are popularly used to create menus but I find them unnecessary. Although they can be useful in providing compatibility with text only browsers.
This page is somewhat inevitably a <div> fest but not too horribly so. Nested <div> elements have been used in place of padding and margin to circumvent the IE box model bug. This is preferable to browser sniffing.
One has to question the success of this experiment. A table based layout would be markedly less complex and not entirely dependent on JavaScript. Tables need not be an obstacle to accessibility. Until the browsers get up to speed with CSS we may be better off with our old ways.
CSS is lacking many things and JavaScript support for CSS leaves much to be desired. The sudden loss of devedge leaves one wondering about how long we have to wait until JavaScript provides a consistent means of reading CSS properties. While the W3C have put their hands up to making a dog's dinner of the whole padding and margin thing Microsoft seem less than willing to resolve the box model bug. Although the answer is obvious, drop quirks for strict XHTML documents, Microsoft seem to have lost interest in developing IE. Is this because IE is now a free product? Perhaps they should release it in open source? That would be an amusing little victory for Mr Gates although it could backfire when folk get to see the spaghetti inside.
Although Mozilla is not without problems such as using the tab key to shift focus is not the same as mouse hovering. To make things worse IE and Opera have different default tab key behaviours. Although Opera does provide comprehensive keyboard shortcuts that can accellerate browser use for all users should they take the not insignificant trouble of training their fingers. Opera provides a useful tool for mapping the keyboard but any deviation from standard leaves you with the old emacs problem when you are at a strange desk and your carefully trained fingers keep pressing the wrong buttons.
Things go rather wierd with this layout when using zoom. Part of the problem is not having a text zoom event to handle the resize with some JavaScript. Another issue is the way that Opera takes a magnifying glass approach to zooming rather than text zooming. This has some advantages but rather more disadvantages notably because this doesn't re-lay the page and brings in horizontal scrollbars, which is not at all good.