Automatic updates of 100-200 of Ubuntu workstations

[Erling Ringen Elvsrud]

Scenario: 100-200 Ubuntu workstations, about 50/50 laptops / desktops.
Most of them used by several people. 

My thoughts:

- A local package mirror (with apt-mirror or something)
- Test updates on a spare workstation before the updates are available
for the rest of the workstations. The X-server problem in Dapper last
summer is one example why I want to test updates first.
- With cron, a custom boot script or something like that run apt-get
update/dist-upgrade, but is it possible to do this without any feedback
at all from the user?

Currently I just update all workstations 1-2 times a year when a new
Ubuntu version is released. I would like to be able to easily perform
security updates more frequently.

Erling