Wiretapping, to use a generic term that includes wired, wireless and other means of snooping, is a commonplace part of thrillers, mysteries and other genres. (Has anyone wiretapped an ansible, yet?) Here is a concise article on wiretapping, that includes modern forms (such as IP/Internet Protocol tapping) and addresses some of the ethical/legal aspects of it. The article has some related sidebar articles on data collection/sensing technology used in mobile phone systems and DRM (digital rights management).

By the way, the article is in acmqueue, one of the Association for Computing Machinery's (ACM's) publications. ACM is a respected professional organization for engineers in the computing industry.