APOS integrating BI and GIS) and I were doing a trade show for ESRI when Brad had a thought. All of this trade show should be in a GIS, not just in a paper map. And you should be able to use it to find what you want and navigate the show.
To which I said, all space can be mapped, including indoor spaces - and not just malls and airports and bus and train terminals, but casinos and libraries and you name it. Including the space between your ears. This is where GIS and CAD show their common parentage.
Another good friend and colleague and GIS developer extraordinaire Kurt Gunther did just this - with hospital beds, in his great eBeds software that manages hospital beds, and the folks in them and serving them, just like they were GIS features.
Today, Google made it real for the average person. "Google Maps 6.0 for Android brings the freestanding map directory to the palm of your hands," announced today on the Google blogs. These detailed floor plans automatically appear when you’re viewing a map and zoom in on a building where indoor map data is available.
For now, the data is limited - Ikea, a few Macy's, the Mall of America, a few major airports. But we all know where we're going. Where Brad said we would, more than ten years ago. And the possibilities, for those of us in GIS land in general, and in ESRI and APOS land in particular, are infinite.