Cell Phone Origami

For what it is worth, placing a cell phone inside of a non-operating microwave works as well.
The same metal shielding that keeps the microwave from cooking you while you watch your food heat blocks cell signals.

CNET had an article on it, and it isn't 100% clear how this is done. If you read the article carefully, it says at times that remote microphone activation is a technique used, and at other times that they are unsure whether it's remote activation or a physical bug planted in the phoe of the Mafiosos in question.

http://news.com.com/FBI+taps+cell+phone+mic+as+eavesdropping+tool/2100-1029_3-6140191.html

Nowhere could I find mention of the broadcast component of the software, only the microphone activation.

Lastly, it says (or at least solidly implies) that the non-foil method of taking the battery out of your phone works just fine.

The CNET article link is excellent.

Removing the battery should work just fine for cell phones with removable batteries. Newer "trac phones" and many other new cell phones have the batteries built-in and cannot be removed. They can only be recharged using car cigarette lighters, or special plug-in adapters. At any rate, if I had a cell phone at a wedding party in Iraq, Yemen, or Afghanistan, a sheet of foil would come in very handy for the safety of the wedding party...