Upgrading to Mac OS X 10.8 Mountain Lion

I suppose you could do it through a policy, and setup automatic restart and alerts saying computer X is going to upgrade to ML. I've done a few computers through Casper Remote just to test and it does work using the pkg that createOSXinstallPkg creates.

From a user point of view, this sounds like a horrific idea. What if they're in the middle of working on a document? What if they have an app that's not ML compatible? Worst, what if it fails, and the computer's OS is borked, and to add injury to insult, the user's documents are now gone without backup, the backup failed if there was one, etc. etc. etc. (completely unrelated issue but let's just play the what if game)

I would have to agree with hkim forcing it maybe a bad idea for a lot of reasons. You may want to set up an annoying pop window that tells them to update it like every two minutes until they do it. Or you could take away some important apps until they do it. Just a few thoughts. I have done it to a machine without user interaction but it was in a test environment, I pushed the installer out to a hidden folder and then used a script to launch it once I knew it was there, but this was going to be more for labs and such.

For lab machines, we'll just wipe during off hours. For staff machines, I setup a policy to cache the installer and then once cached, have a self-service policy to begin the installation. That way staff can do it on their own time and don't have to download the 4GB package from distribution point. We are only still testing this but have upgraded from 10.6.8 to 10.8.2 in about 35 minutes or so. I used the method here http://managingosx.wordpress.com/2012/07/25/son-of-installlion-pkg/ and it works great.

We don't even give our users access to upgrade via Self Service. We push out the installpkg manually once we have verified the user is backed up to CrashPlan. Plus our users are "special" and like to disconnect their laptops from the internet during the download. Just something to think about. I'd manually push it out, if I were you.