First of all, I'm new to LinuxQuestions.org, so if I'm asking a frequently asked question, I'm sorry. I've tried the search but couldn't find anything about this.
I've got an idea for x.org/$randomwindowmanager in combination with a multiheaded setup, but I haven't figured out how it should work. Also I don't really know where to place the feature request.

Now for the idea.
I've been working with screen (wikipedia:GNU_Screen) for some years now. One thing I like about it, is the fact that I can get a multi-display mode (screen -x), so you can have multiple terminals all connected to the same screen. The fun thing about it, is that you can get 2 terminals with the same content and switch my onscreen layout, without moving the terminals. I admit, in screen it's not extremely useful, but I think for a wm it can be.

Imagine this. You've got two monitors and 4 workdesks. On one workdesk I've got my IDE with code, on the second one I've got the output, on the third one I've got the documentation and on the forth one I've got my e-mail and IM clients. At one moment, I want my IDE and output on my monitors, another moment my code and documentation and Yet another moment my IM to consult a colleague and documentation or code. Finally my colleague comes to help me at my desk. I'd like it if we could both watch the same workdesk without him sitting on my lap, so I turn one monitor so he can see it better. It would be great if we could see the same thing that's on my monitor (exclude mousepointer).

The thing with most WMs is that your workspaces on the two monitors are either separated or glued together. If they're separated, you can change workspaces on each monitor autonomous, but you can't exchange applications between monitors because they're different x-clients (iirc). If they're glued together (xinerama), you can exchange the applications, but when changing your workspace, the other monitors change too.

So, what I'd like to know is this. Is this already possible or should I submit a feature request somewhere (and if so, where?)

Thanks for listening

I think that would be asking for trouble.

Having even two independent window sessions (i.e. kde) by the same user at the same time will cause contention problems. This is even if you operate at two different X terminals. One session may also create a lock file somewhere, and then the other will not proceed, obeying advisory locking.

The desktop environment will also have a daemon running in the background. For example, the hal helpers that are used to communicate what you want to do with a pendrive you inserted. Which kde session for the same user does this daemon communicate with? How does kde use the same sockets in ~/.kde/ for two separate sessions?

But you would get the same problem if you're using x.org without xinerama. Haven't done that in years, though..
I think locking isn't the biggest problem...

You can have different screens. For example, simply precede a command with "DISPLAY="0.1 " and the command will use that screen. You can even add this to the "command:" entry of an icons properties. Then when you click on the icon, the program will open up on the screen you want. YOu can even have it open on another computer, if you use xauth to allow it. There is also the "-display" option. You can run "kate --help", for example. Some of the options are kde (or gnome) options. Also look at --help-qt.

I have done this where I had a terminal in one screen; editing a latex document, and running latex from inside vim. The finished document would be updated in kdvi on another monitor.

When you said "workdesks", I took that to mean desktops.

That will help with the windowplacement, but that doesn't solve the problem. I don't want my windows to be bound to a certain screen.
I would like to bind my programs to a workspace and tell my screen which workspace it should display. So... it would prolly be something in a windowmanager, right?

Yes, but sometimes desktop is an ambiguous word and my wm calls it workdesk

You are looking for a function of the window manager and not X11. For example, instead of a desktop switcher on the same screen, have desktops on different screens. I don't know if KDE or Gnome can be configured this way.