... by someone driving by in a car, if those documents have RFID chips installed in them.
A fellow in San Francisco installed an RFID reader in his car, with an antenna, and connected it to his laptop on the front seat. He then drove around the city and was able to pick up the signals from passports and driver's licenses and have the information downloaded to his computer. He could then upload the data to clone the passport.
The person doing this is one of the "good guys." He's demonstrating for the world how insanely easy it is to steal information from an RFID chip, and he's hoping to convince the public (or, more precisely, lawmakers) that RFID should not be used for personal identity tracking as the Department of Homeland Security wants to do.
There is a video at the Engadget link.