For the most part these days, sharing calendars can be very easy with the likes of Google Calendar and iCal/iCloud. Of course, when people you share with use other calendar apps it can be difficult. Even more so when trying to share a calendar using an Exchange Server and Outlook 2011 (Microsoft Office for Mac 2011).
This task appeared impossible if we wanted the other users to have any editorial rights on events. Viewing a shared calendar was easy but still not perfect as you would see all events on all of the originating user's calendars. Selecting ONE calendar to share is not an option.
Since the client is well-entrenched in the use of an Exchange Server at the time and all staff are using Outlook from Office for Mac 2011 (and a few with Office 2008 - Entourage), we started to mess with some settings. The first step we took when this request was brought to us was to simply assign the other employees as delegates for User 1's calendar. As already stated, this resulted in a fail because ALL events from ALL calendars and ALL categories showed up. User 1 just wanted ONE calendar group to show up for the other staff to see/edit. Even at the start of it, we had permissions/viewing issues to which we had to have Intermedia, the Exchange host, rectify from their end. Not sure why. And, not only did the other staff see all events, they could not edit anything, which is what this situation required. Double fail.
So then we sat on the issue a few weeks. We looked into using Google Calendars in Outlook but you could not get a Google Calendar in Outlook at the time. We looked at the option of using something like Spanning Sync to sync iCal and Google, then iCal and Outlook could sync using the built-in sync services of Outlook. From our experiences though, this method can be unreliable when you have heavily used calendars. I used and loved Spanning Sync for years until iCloud was released and now find that I can drop Google and JUST use iCloud/iCal. When using Spanning Sync and trying to cross multiple calendar apps and accounts, syncs get stuck, events get dropped and this situation simply cannot afford the 95% success rate. They need this to "just work". Understandable!
Then it dawned on us that they had a couple Exchange accounts that were being used for very little, if anything; an intern account and a copier account. No email was usually coming in to these accounts and no one was accessing them for any reason. So we setup the account on one of our own Macs and setup a calendar. Instead of creating the staff as delegates for just the calendar, we created the other staff as delegates of the whole user account. You can do this by accessing the Outlook menu item in the menu bar, then Preferences > Accounts > Advanced (button at bottom right of account window) > Delegates tab. Hit the plus sign to search for names and add delegates. After locating another user, adjust their permissions to be "Calendar: Editor". All other items (tasks, inbox, contacts, notes) can be left as "None". THIS allowed the other staff to open the calendar (in Calendar view, Open Calendar) of this user AND gave them full editorial rights.
Why this is different than accessing delegates and permissions directly via the calendar itself is beyond us (control-click or right-click on a calendar > Sharing Permissions). Now, if you go to the calendar and view the permissions, everyone will be listed there as an Editor. However, setting it up from that method didn't seem to give us the correct results (other users could not edit, only view). So by using a "ghost" account, we successfully gave all other staff delegate access and they could view, edit and add events to the "shared" calendar and did not need to see any other unnecessary calendars of other staff members.
As a sidenote, based on one staffer's request, we also found out that for whatever reason, in Outlook 2011 for Mac, you cannot change the color of a shared calendar. They are just blue. Like it or not. In the end, we rarely recommend the use of Outlook for any clients due to various limitations for other services (which actually got worse in the 2011 version) and we certainly do not recommend it if they're NOT using an Exchange Server, as that is what Outlook is designed to be best at. If they are using Exchange, then Outlook could be the answer to them, although Mail will work just fine with any service and is often easier to setup with automated settings than Outlook.
For more on the limitations of Outlook, here's an article from Microsoft. For details on what Outlook (and other Office 2011 applications) can and cannot do, integrate with and provide, here's an extensive article on Macworld's site.