Graphical workspace switcher?

Hi,

I've been using Sawfish since it was sawmill and part of Gnome.  I
recently took a divergence into Unity+compiz just to see what that was
like.  Now I'm back to the comfort of sawfish (+MATE).

There were some things about Unity that I liked.  One was the
graphical workspace switcher (don't know the correct name) where you
can type Super-s and see the entire NxM grid of workspaces spread
across the screen along with their contents.  Then, either a mouse
click on the desired workspace or select it with the arrow keys and
ENTER to pick it.  I've played with the sawfish cabinet which is only
recently news to me.  It's very nice and gives this kind of global
view, but this workspace spread thing that Unity has offers more
visual clues about which workspace is wanted.

I don't suppose someone has cooked up something like this for sawfish,
have they?

If not, does anyone have an estimate of the effort needed to develop it?

Cheers,
-Brett.

-- 
Sawfish ML