Raspberry Pi + RFID Reader + Cellular Data Card = Nefarious people Tracking guests' Magic Bands as they enter and leave a resort. Nothing like telling the crooks that you are leaving.
I am not worried about Disney using the information as much as I am about the ability of someone putting a transponder on my wrist that any yahoo with $50 in parts can read and track my movements and patterns.
http://www.youtube.com/watch?feature=player_detailpage&v=FgQjsUUiNrE
The MagicBands transmit in the clear and not encrypted because the bands are only transmitting a unique ID number, like a serial number. The distance a band can be read is determined by the Antenna on the reader and the antenna on the band. The band has gain of +/-0db, so the power of the reader antenna is what determines the distance that the band can be read. a 12db antenna will have a theoretical distance of around 10 meters. A 20db antenna (Yagi or Corner reflector) will be able to read your MagicBand at 20 meters.
Disney is only considering the direct impacts of RFID and not the indirect impacts.