Spatial Privacy - What is it? What should it be?

I have been asked to give a talk on privacy and spatial technology in December to a group of lawyers interested in the legal aspects of remote sensing. Before putting together my remarks, I am very interested in learning what those in the spatial community think privacy is in a spatial context, and just as importantly, what it should be. It is an important topic for the development of spatial technology. However, it has not yet been codified, in the U.S. at least. in any meaningful way. As a result, one is forced to look at other areas of law for guidance. For example, if and when should a person have a "reasonable expectation of privacy" with respect to his or her location? Should there be a "reasonable expectation of privacy" with respect to a particular person or group, such as a spouse, an employer, or law enforcement? Similarly, should location-based information be subject to the same legal protection as "personally identifiable information" -- such as credit card information or medical records? I encourage you to provide your thoughts and comments below.