The MSExchage team has shown us five activities of ADUC/Exchange2003 Admins and how they will be executed on Exchange Server 2007.
In Exchange 2003, Active Directory Users and Computers (ADUC) was the place to go for recipient management. This was frustrating to some, as it was a management environment totally separate from the Exchange system management console. In Exchange 2007, this recipient management functionality has been integrated back into the Exchange management tools, both in Exchange management shell and in Exchange management console.
Read more at source: http://msexchangeteam.com/archive/2006/09/29/429043.aspx