We just got our new credit cards, and it was brought to our attention that there's an RFID chip inside! I read a FAQ about them, and apparently they broadcast a small radio signal that stores (as well as thieves) could pick up on.
Talk about a privacy violation! As I walk down the street, my credit card is broadcasting my first and last name, credit card number, etc.!
Anyhow, I just wanted to let you all know -- that you simply need to bash it with a hammer, pierce it, etc. to disable it. We disabled ours.