The Unity Dash serves as a viewer for all kinds of content
Search is also possible
The Launcher provides shortcuts to the most used programs
Those are the tasks traditionally happening on the "desktop" or "Workspace". With the Unity Dash and Launcher doing the job actually better(searchability, sorting after content type), the actual desktop is not necessary anymore.
Right now, there is the desktop, and if you want the Dash, you have to click. The Dash has the focus, but can lose it.