Check out this interview with an NSA whistleblower who alleges that the government is spending billions to collect and store everybody's email, which they could at any time presumably read and analyze.
While it is arguable whether a warrant would be needed to view any of this raw data, it is especially worrisome when one considers it in light of the sudden domestic use of drones by law enforcement, the drive to put black boxes on all cars to report on our movements, cameras and microphones on buses, and who knows what else.
The only real trustworthy solution is to make illegal all of these things, or at least to require the government to get a warrant before any access to this is legally allowed.
Is this not the possible foundation for tyranny? For a state that rules it's citizens with the threat of investigation using all possible forms of communication, in or more probably out of context?
Bring me my Scotch, cause I am going to need it.