The desktop toolbox, accessed via the top right corner has a button for zooming out. Plasma allows you to have more than one activity. Basically, that is multiple desktop containments hosting multiple sets of Plasmoids. Zoom out from your current activity, choose Add activity to create a new containment, zoom in to your new containment and customize suiting your taste. Plasma's zooming and KWin's desktop grid are similar in that respect, but there is a fundamental difference. While virtual desktop are used to group and organize windows, Plasma's activities are used to group and organize plasmoids. This way, you can switch between activities and have relevant Plasmoids supporting the task you're currently trying to accomplish. You can create a "Free time" activity, with comic strips, a puzzle and other Plasmoids, and a work activity, with relevant RSS feeds, calculator and calendar, for example.