Day: A New Approach to GNOME Application Design

Well, you should probably investigate the Activity concept of KDE4, then. You can fast-switch between activities using the keyboard (or icons, etc), and it works sort of like virtual desktops with extra functionality.

It is orthogonal to the other fast-focus-switch axis, and groups things by, well, activities. I am quite sure the concept has not been explored to its best yet, I need to test the latest KDE to see how much it improved lately.

Maybe they can add activities or something like that to the gnome-shell, it is a far superior way to group a set of *windows* (the same application can have windows that belong to different activities, after all. In fact, it is almost the rule for the browser, text terminals and text editors).