Google Apps for Education is a powerful set of tools for collaboration.
Using "Groups" in Google Apps allows users to be assigned to their working or interest groups.
There are two ways to do this in Apps, and it is useful to point out the difference.
Contacts allows mailing lists to be made AT THE INDIVIDUAL'S LEVEL. Here you are able to name a list and assign people in your contacts to the list.
Groups, if properly set up, allows users to make a working or interest group at the institution level. This is really powerful because it allows permissions to be assigned for Google Docs or Google Sites by using Groups - no one-by-one individual assigning.
Additionally, changing the original Group list will change the permission for the Doc or Site - no need to go back to individual Docs or Sites to edit the permissions.
Fernando, our excellent Systems Manager, explained to me how Groups works at this school (we call our Apps system "dash net" to differentiate it from our previous mailing list system).