I don’t normally comment on other people’s software… but… a little while ago, opensuse was wondering whether KDE apps would work with these Gnome Shell requirements. Last time I checked, their “Activities” sounded like virtual desktops, but now they’ve returned to an application-based shell. This in sharp contrast to Plasma Desktop’s increasingly Activity-oriented workspace.
So what does that mean? Well, in gnome-shell, windows are organized by application – by the binary that spawns them. All your firefox windows are grouped together, all your okular windows grouped together, etc. You can still group windows on virtual desktops, but alt-tab is application-based, so as soon as you’ve got more windows than screen space you may as well have everything on one desktop.
Read the full thing at http://chani.wordpress.com/2010/12/26/activity-oriented-vs-application-oriented-workspaces/