From the official Google Apps blog…
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Google Apps administrators can now segment their users into different organizations and control which Google services are enabled/disabled for each of those different sets of users.
– Allows creation of organizations in a tree-like hierarchy
– Manage membership of users into one organization
– Specify policies for which services are on/off by organization
Updates have also been made to the Google Apps Directory Sync Tool and the Provisioning API to take this new functionality into account.
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You can read more about this update here: http://googleappsupdates.blogspot.com/2010/07/user-policy-management-now-in-google.html
One last thing…there is a catch to using this. A user can exist in only a single node in the hierarchy tree. This could present problems for users who have multiple roles (ie. a graduate student who is also an undergraduate alumnus, a staff member who is also a student, etc.)
-Chris