The first problem with having multiple 404 pages, each dedicated to a particular area is that you assume users were in the right part of the website at the point when they fell on to the 404.
Bearing in mind that many links come from search engines and not necessarily from within the website, then I don't think you can guarantee that a dedicated 404 is always going to be the most helpful option for all users.
The second problem with multiple 404's is you are immediately increasing or duplicating the number of places you need to keep up to date or maintain. At some point you'll almost certainly have to decide that you'll have dedicated 404's about specific topics A, B, C, but have a generic 404 for 'everything else' and this generic 404 should probably include topics A,B,C anyway!
Apple's take on the 404 groups the possible forward options into the same group structure as the top level navigational structure.
So yes you come to one page, whatever the location that the error happened. But that's ok because it's easy to see links related to the section you were in, or wanted to be in. You can also easily see what the other sections are about in case this helps give a higher level picture.
In fact - Apple's 404 is so helpful, I'm almost tempted to bookmark it and deliberately go to Apple's 404 page in order to kick start my way around the site! It's not as long or detailed as their sitemap but is (in my opinion) easier than browsing via their top menus which aren't drop downs.
EDIT: Compare Apple with Bloomberg's 404 for example, which totally puts a lot of effort concentrated on the absolute wrong thing to display. It's animated so you have to see it to believe it. Weird!