If you, like me, use FasTrak, this article from the Hack a Day site should give
you pause. Turns out that, like our new RFID U.S. passports, our FasTrak
transponders are also very easy to tap into and for even lazy hackers,
gives access to personal information, among other things.
Keep you transponder in its mylar bag when not in use, or in tinfoil…
http://www.hackaday.com/2008/08/06/black-hat-2008-fastrak-toll-system-completely-broken/