This white paper provides the information that you need in order to configure Microsoft Exchange Server 2007 with multiple address lists so different groups of users can have their own address list and secure those address lists so that groups of users can only see their specific address list.

Much of the information in this white paper originally appeared as individual Help topics in the Exchange Server 2007 Help. In this white paper, we have consolidated the information that you need to deploy and manage segregated address lists in one central location. We have also provided sample scripts, which can be modified to fit your environment, to help automate the provisioning of virtual organizations and users.

http://technet.microsoft.com/en-us/exchange/bb936719.aspx or
http://technet.microsoft.com/en-us/library/bb936719(EXCHG.80,printer).aspx

More technical papers: http://technet.microsoft.com/en-us/library/cc164340(EXCHG.80).aspx