Alex and I have been working on this for some time and will be releasing it soon.

*UPDATE: It's here: http://jacob.steelsmith.org/content/ubuntu-kiosk-based-10041

Implementation for kiosk.

1). Changed the homepage of the kiosk user to an allowed website by editing /home/kiosk/.mozilla/firefox//user.js

2). Installed and configured dansguardian using the directions here:
http://ubuntuforums.org/showthread.php?t=207008

a). sudo apt-get install dansguardian tinyproxy firehol
b). Change the user's home page in firefox by editing /home/user/.mozilla/firefox//user.js
c). edit /etc/dansguardian/dansguardian.conf and comment the line that starts with UNCONFIGURED

I am working on a kiosk build using Ubuntu 9.10. I will post the iso shortly.

A work order had come through at my work several weeks ago stating that one of our public kiosks was prompting for credit card information via the browser whenever a user attempted to use it. This was supposed to be an "internet only" kiosk, which turned out not to be, but was definitely supposed to be a locked down machine.