Nor cars, space travel, or radio and television. Or travel by steamship, or trains, or aeroplane. And your point is... what, exactly?
That communication has gotten faster, and more efficient? So the Bill of Rights should be thrown out wholesale because of technological advances?
The Founders could not have envisioned firearms with bullets and powder combined into single cartridges. Should they be banned because the Founders couldn't see every advance that was coming?
Should you give up your car because the Founders couldn't concieve of horseless transport?
Need I go on?
My point was that I don't think the Founding Fathers could have envisioned the electronic eavesdropping thing - period - to the point where everyone's private conversations are now sort of automatically invaded by NSA/Echelon.