This can be done fairly easily, without too much hassle, it just depends on how sophisticated a solution is required. For example, the group calendar functionality will achieve quite a lot of this sort of thing with nil development effort.
Otherwise, collecting C&S data from other calendars and collating it in one calendar isn't too bad, especially if this is cascaded (i.e. one "collector" grabbing individuals' data and putting it into a dept. calendar, then "department collectors" working from the dept. calendar(s) to your organisational one).
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