You're talking about miniature faking, right ? I recently encountered it too, by following a link from a Lego trains site. As I understand it, the effect can either be done through a special lens, or by computer manipulation (by selective blurring).

In any case, it's all about making real stuff look like a miniature diorama, not the other way around. Though of course, if you know what to do to make a scene look like a diorama, then you also know what to avoid to make a diorama look like an actual scene.