Change the *default *configuration in Sakai 11.0 so that the option to allow all users to 'privately' publish (the 'Publish (Private)' button) site calendars is always shown in My Workspace and exports all the users collated calendars in one feed. This property is called 'ical.myworkspace.auto.export'.
This is notably distinct from the 'Publish (Public)' facility as the URL that is generated here is un-guessable and is NOT meant for public circulation. If compromised, it can be regenerated. It means that users can subscribe to their My Workspace (ahem, sorry, 'Home') Calendar which, of course, includes a collated view of all their sakai site calendars.