Apparently if you have a CC with a RFID (radio frequency) chip in it, someone with a scanner can get close to you in a crowd and pick up your CC number and exp. date while the card is in your wallet.
They did not say it has been done, just that it is possible. There is symbol on cards that are so enabled, I checked all mine and none of them are. If you have one of those cards you just have to hold it near (not slide it through) when you are buying something. Sort of like a Speedpass. That is what I got out of it.
PS the symbol looks sort of like this )))