There was a "warning email" going around about this kind of theft. Wikipedia has a good bunch of information here: http://en.wikipedia.org/wiki/Wireless_identity_theft

Apparently new scanners can read the chips from about three feet away.

Also - credit card manufacturers are on to this and making changes. Might be an idea to call one's card company and see what they have for safeguards.

Nevertheless, after public disclosure of information that could be stolen by low-cost jury-rigged detectors which were used to scan cards in mailing envelopes (and in other studies also even via drive-by data attacks), the design of security features on various cards was upgraded to remove card owners' names and other data.[1][10] Additionally a number of completely unencrypted card designs were converted to encrypted data systems.[1][10]