From
Status-Q: "Fortunately, Kovid Goyal came to my rescue with a system called librs500. He’s reverse-engineered the Sony protocols and created a Python-based library and utilities that can transfer files to and from the PRS. Sony owe him some money - the profit from my purchase, at the very least! You need to install a few bits, like Python 2.5, to use libprs500 - the easiest way is probably to use MacPorts. Once you’ve got libprs500 installed, though, you can start to do fun things."