This section is a bit of a catch-all; these are settings that apply to your entire organization, and don't easily fit in anywhere else.
Organization
Sharing
Sharing settings control the sharing of Exchange information (specifically, calendar information such as free/busy, and more detailed information about appointments) with people in other domains:
Sharing settings
You can create a relationship between your organization and another one that will apply to either all of your users, or a specific security group:
New organization relationship
You can enable the sharing of free/busy information with the time only, or with the subject and location, as well. Limit sharing to a specific security group, or apply it to everyone...