I have made a tiny open source software called PRS Note Reader which could read the .note format (both of text and drawing) used in Sony PRS reader , and it also can convert the file to svg or text file. Now it run on Debian or Ubuntu Linux. As it use Python and QT as the platform (just like Calibre) , should be portable to Mac and Windows.
You may download the .deb file from the site above , or add the following source repository to your APT.
deb http://ppa.launchpad.net/benlau/ppa/ubuntu jaunty main
sudo apt-get install prsnotereader