...I tried to warn folks about their 'indispensable' cell phones and how I barely ever use them.

To be quite honest it's not the Feds you have to worry about eavesdropping - its corporate employees of firms like Nextel who get a kick out of listening in on celebrities, politicians, neighbors etcetera.

Feds don't have the time or resources to waste on eavesdropping on the public - whereas corporate employees often do.

Don't bother taking the battery out of the phone. Just adjust your volume setting to zero (on phones so equipped) or 1 after you finish up a call. Then turn up the volume again after the phone rings. Most phones if activated to act as a listening device will be using the users preset volume settings when transmitting.