[boomlinde]

> If not, what is the fundamental difference between what I'm doing by observing people that walk or drive by on my street and what Facebook does by observing what its users do on its site?

The expectation of privacy. The window analogy may seem very clear to you, but a lot of people see Facebook as a sort of postal service carrying their enveloped messages to their friends, and they have to trawl through a pretty large document of legalese to find out how it isn't. Facebook is more like one-way mirrored glass.