I wanted to use the foton.py utility for my NB tool, and I remember Chris telling me that it was shipping as standard with the newer versions of gds. It wasn't available in the versions of gds available on our workstations - the default version is 2.15.1. So I downloaded gds-2.17.15 from http://software.ligo.org/lscsoft/source/, and installed it to /ligo/apps/linux-x86_64/gds-2.17.15/gds-2.17.15. In it, there is a file at GUI/foton/foton.py.in - this is the one I needed. 

Turns out this was more complicated than I expected. Building the newer version of gds throws up a bunch of compilation errors. Chris had pointed me to some pre-built binaries for ubuntu12 on the llo cds wiki, but those versions of gds do not have foton.py. I am dropping this for now.