Allowing more than 1 user to manage the group membership of a Exchange 2007 Distribution List

http://technet.microsoft.com/en-us/library/cc164350.aspx

As with most simple things in Exchange 2007 this needs to be done using powershell. It's fairly simple once you know the commands though, see below for the Microsoft example.

Use the Exchange Management Shell to delegate management of distribution group membership to a user

Run the following command:

Add-ADPermission -Identity -User -AccessRights WriteProperty -Properties "Member"
For example, to grant John Smith the right to add members to the Marketing Department distribution group, run the following command:

Add-ADPermission -Identity "Marketing Department" -User "John Smith" -AccessRights WriteProperty -Properties