Here is their main intro. Controversy concerning the quality of anonymity is described here. Michael Froomkin has written on legal aspects of digital anonymity. Here is a protocol that I devised that was inspired by early rumors of the Mondex card.
Stories about a break in to Mondex.
Stuff above was written when Mondex was just a couple of years old. A search today (Sept 2005) yields these notes. 1997 June Overview; 1998Australian trial; History site; At MasterCard