Virtual (Smart?) Application Folder

Question

I know there are three preferred locations for applications to reside: /Network/Applications (network apps), /Applications (system apps), and ~/Applications (user apps). By default, my Dock's "Application" folder is just a link to /Applications and thus just shows the system apps. Is it possible to create a virtual folder which displays the combined contents of all three application folders, rather than having to access them separately? This way, the user doesn't have to remember which folder contains a specific application.
Thus far, I have made a Smart Folder and customized its property list (by editing the raw .savedSearch file) to search the above three directories. However, this recursively searches all subpaths, so all apps in /Applications/Utilities appear at the top-level of the Smart Folder. Ideally, this wouldn't happen, and the Smart Folder would basically be a copy of the root-level contents of the application folders. Here's a concrete example of what I'm looking for:
/Applications:
App Store.app
Automator.app
Utilities/
/Network/Applications:
Firefox.app
~/Applications:
Eclipse.app
Fetch.app
Virtual Application Folder:
App Store.app*
Automator.app*
Eclipse.app*
Fetch.app*
Firefox.app*
Utilities/*
* where all these guys are aliases or symlinks.
Is this possible with Smart Folders? If not, is there another virtual folder abstraction available that can handle the job?

Answer 1

Thanks for the response, Barney. Yes, on a typical system, /Applications is for all users and ~/Applications is user-specific. I was trying to indicate that, in a networked environment, /Applications is for all users on a particular system, rather than all users on the network. The discussion can be restricted to just /Applications and ~/Applications, though, since any solution should easily be able to add /Network/Applications to the list of search paths. Also, I just picked the locations for Firefox, Fetch, etc. arbitrarily.
Ideally, I'd like something that transparently updates when any of the Applications folders is modified. In other words, if I add something to /Applications, it shows up in the virtual folder immediately. Manually creating aliases or symlinks isn't going to achieve that. I could easily write a script to regenerate the folder on modification, but I don't know how to invoke it when any of the sources are modified.
Also, since I doubt I can have my cake and eat it too, it's ok to have a smart folder which opens in Finder, rather than presenting the items via the Dock. Bonus points to circumventing this, though.