There was actually an example before the A List Apart one (in terms of a UL based css menu system), but that discussion was beaten to death in the responses on A List Apart, so there's little merit in reopening the discussion. Yes, more or less this is the same thing as the List Apart UL menu. Also, if I remember correctly the RT I used -while not the DHTML MENU rt verbatim - was based off of your original RT, so kudos to you.
The difference between this and the one posted previously is that this one includes comprehensive style classes to allow control over all menu styling, going FAR beyond anything provided in any previous script, including anything provided by A List Apart (whose menu only goes one level deep) or the Suckerfish reworking that provided multiple levels.
In essence the styling on this menu is more or less something entirely new that, in my mind, makes this menu MUCH more useful. Its possible to say "well, this is just CSS", but I would say "look at the complexity of the actual CSS, look at the complexity of the inheritance structure employed, and look at how the menu bahaves IDENTICALLY in IE and FF".
For example, this script uses the more robust DHTMLMENU2 include which basically adds the ability to write certain ID values, while your RT and menu don't provide any ability for unique IDs.
Another example, this one allows for "in" states, while the one you provided doesn't (in states are states when the parent element for a child menu is open). How, in your original script, do I know which menu the open item referes to when I'm in it? Answer, I don't. This is actually a big difference and took a lot of effort to get working in both FF and IE.
And FYI, DHTML (Dynamic HTML)
IS Javascript + CSS + HTML. Any solution employing a combination of all three to provide for complex interactive bahaviors is, by definition, DHTML. As you yourself highlighted in the very first paragraph of your post, this menu uses all three.
http://encyclopedia.laborlawtalk.com/DHTML
Let me know if I can provide any further clarification on other technology terms, etc. I have access to google and the brainpower to search for the definition to terms before correcting people regarding their use.
Ta ta,
Rick