Not that I know of. But you can force the desktop to lock when the screen saver engages. That way the user has to enter a password when he returns to his desk. It's not a full log off, but it's close. But forcing a log off could cause users to lose data because forcing it would also force applications closed. And if that were to happen without prompting the user to save changes, you could have unhappy users.
Well, thats the problem, in house I have a computer that multiple users use, but most times users doesn't log out. When another user wants to use it, it can't because it is locked and it doesn't know the password. I disabled user switching, because it led to freezes.
So, basically I have to create a script that does polling (e.g. once per minute) and if it detects screensaver running, then it forces logout procedure. I wonder if it will work, when screensaver is running.