I'd argue the third ammendment is more rightfully seen as a ban on government surrveilance of it's citizens.
Is their really a difference between a private siting in the living room listening to your calls and an FBI agent doing it remotely.
[t]he 1947 House and Rent Act [a rent control measure] as amended and extended is and always was the incubator and hatchery of swarms of bureaucrats to be quartered as storm troopers upon the people in violation of Amendment III of the United States Constitution.
Extending that to modern electronic surveillance is not a big step, nor out of touch with the purpose of the 3rd Amendment.
Actually in discussing this (hilarious) Onion spoof my wife made the point that this could be related to imminent domain.
Had the telephone existed at the time the BOR was written, I have no doubt that a prohibition on the government monitoring telephone calls (at least without a warrant supported by probable cause) would be amongst our most cherished protections from the government.
The FBI agent's more likely someone bored to tears that they got stuck on the wire
Eminent. Em. Totally different. Eminent, not imminent. (weakly) please... em...