The idea of the government listening to telephone conversations just doesn't bother me.
First, I have nothing to hide. Listen all you want. You'll hear me talking to my parents about the weather, the local basketball team and their vacation plans.
Second, if listening to these conversations prevents a crime from happening, be it a terrorist attack, an illegal drug transaction, a murder/assault/kidnapping, or even two pedophiles talking about the little boy and/or girl they have tied up in their basement, then I want those conversations being monitored.
Everyone screams now, but the first time something huge is prevented, or a child is saved, everyone will be thankful.