http://www.engadget.com/2008/09/02/mythbusters-rfid-hacking-episode-canned-by-credit-card-company-l/
I knew a kid freshman year who had an RFID reader/writer/spoofer setup that worked... he was a raging paranoid and never had a facebook account, but man he was good. He quit school about a year in to go work for some company I'd never heard of at the time... and at the time I didn't really keep up with the technical world...
I think that PumpingStation1 has an RDIF reader/writer/spoofer setup... I kinda want to play with it. what kind of software goes with that? It's soooo bitlevel, though... -sigh- I'm not really about the bit-level... but understanding it would be emotionally rewarding. Bah.