I've read the article below which has an example script that creates a child management role. I've run this in my environment and it works create with one big exception. As best I can tell the owner of the group has access to change the group name and the alias (which would essentially change the email address). Is there a way to take this a step further and allow owners to add / remove group members, but not allow them to change other info about the distirbution group?
http://blogs.technet.com/b/exchange/archive/2009/11/18/3408844.aspx