There is currently an international effort to force the manufacturer's of encryption techniques and products that use encryption to provide the government, both domestic and abroad, real time key escrow to encrypted communications.  This naturally includes encrypted electronic communications which occur between a contactless smartcard reader and your smartcard.  Since logging a persons identification and location is not considered an invasion of privacy, the government will soon have the tool it needs to track your movements whenever you are within range of a reader.  Granted, your identification and location can be logged anytime you use your credit card, but YOU decide when that occurs and it can not occur without your knowledge.  Incidentally, it is the U.S. Government leading the charge on this one.

Furthermore, even though Smartcard manufacturers are concerned about their operating systems and encryption techniques being compromised by theft or internal corruption, they are even more fearful that government employees with access to the encryption keys will sell out.  Any legislation that expands the number of people with access to sensitive security information only increases the likelihood that abuses will occur.

Contactless smartcards are very much like trojan horses.  They offer convenience and the promise to simplify your life.  All it may cost you is your privacy.  Ultimately, you must decide whether you consider this intrusion into your personal life acceptable or not.