The virtual camera is as much a concept as it is a technology. A conceptualization of the camera as a spatial occupant, present but incorporeal - in the space but not necessarily of the space and more often than not, in defiance of the space and of physicality. Obviously these conceptual parameters would point directly at the specific 3D graphic technologies that allow for the virtual camera. But this is not to say that the same Virtual Camera concept is not also viable with physical cameras.
The increasingly famous car chase scene in Children of Men is one such example. No effects, no greenscreen, no 3D virtual camera or set - instead a highly elaborate physical construction to allow for an otherwise physically impossible shot. But more interesting than the fabulous mechanics is the spatial effect on viewership.