More info on that in the DataObjectManager forum.
Run another update on the event_calendar, as well. People using the default theme need to remove the sidebar from the event detail view. I've removed it from the default CalendarEvent.ss, but you really should be using your own templates to customize the look of your site.
Please note, "announcements" do not get links to detail pages. Only calendar events do. The use of an announcement is for something like "Office closed today" or "John's Birthday" .. things on the calendar that do not need details.