add shared calendar alerts
Whenever somebody makes a change to a shared calendar, the other subscribers/the owner of the calendar should be informed via a "shared calendar alert". Apple offers this very valuable feature on iCloud for both Mac OS X and iOS.
We’re interested in supporting this and in fact we already support some bits and pieces of this notification functionality (e.g. when someone invites you into a calendar), but unfortunately this is not a standard yet (it’s an Apple extension: https://github.com/fruux/sabre-dav/blob/master/docs/caldav-notifications.txt).
These change-notifications don’t seem to be supported for third parties at the moment.
We’ll keep an eye on this as Apple releases newer versions of its operating systems (iOS7/OS X Mavericks).