We are using Google Apps with Gmail and Calendar. The default settings for calendar visibility is set to shared, all internal users can see each other.
The task is to create a new user with limited access to other internal user calendars, the new user need to be able to see details about bookings/events only for a few specific calendars.
This is possible if I change the default visibility behavior so you always have to ask for permission to see any other calendar. But with a few hundred users who should have access to each other, this is not a valid solution.