I knew iTALC, but i'm doing an easier-to-use homemade version for our teachers.
I already reproduced almost every features, but in a different manner. And it uses "only one computer", as all stations are booted via PXE.
Of course it is Slackware-powered.
I intend to make it available as a disk image to all, when it will be 100% tested and operationnal.
Anyway thanks for your answer and your numerous links !!! I'll browse them to include whatever useful.
You can add this to your list:
For the xscreensaver part, i used this : xscreensaver-command -lock
It works like a charm, except for the login screen, which appears when an input event occurs, but it's np :^).
OSS 4 4LL :^)