The latest attempt to answer privacy concerns with RFID: RFID “blocker tags”:

RSA Security on Wednesday outlined plans for a technology they call blocker tags, which are similar in size and cost to radio frequency identification (RFID) tags but disrupt the transmission of information to scanning devices and thwart the collection of data.

The technique, one of few RFID-blocking technologies being worked on by researchers, is still a concept in the labs. But the next step is to develop prototype chips and see if manufacturers are interested in making the processors, according to Ari Juels, a principal research scientist with RSA Laboratories.