The desktop metaphor itself has been extended and stretched with various implementations, since access to features and usability of the computer are usually more important than maintaining the "purity" of the metaphor. Hence we find trash cans on the desktop, as well as disks and network volumes (which can be thought of as filing cabinets - not something normally found on a desktop). Other features such as menu bars, task bars or docks have no counterpart on a real-world desktop.
In recent times the filing cabinet and desktop metaphor has become less important, especially since the advent of very large storage media, which can make the easy navigation of files and folders problematic. A more user-oriented approach is gaining favour, where the user can organise documents in a manner that facilitates his or her particular needs, rather than being forced to use a file-system view of the system. The addition of "smart folders" and the like leads to a method of locating files that is based on search criteria important to the user, rather than its physical arrangement on disk, which ultimately is of no importance to the user.
The first computer to popularise the desktop metaphor over the earlier command line interface was the Apple Macintosh of 1984. See also History of the GUI. And also desktop environment.