Delegate the enable/disable accounts permission in Active Directory

To delegate the ability to enable and disable user accounts in Active Directory:

Launch Active Directory Users and Computers with adminsitrative credentials
Right click on the OU where you want to delegate the ability to enable and disable user accounts
Select the Active Directory security group that you want to delegate the ability to and press Next
Select Create Custom Task to Delegate and press Next
Under Delegate Control Of select the Only the following objects in the folder radio button
Select the User objects check box and press Next
Under Show these permissions uncheck General and select Property-specific
Select the Read userAccountControl and Write userAccountControl check boxes and press Next and Finish

Hoe to convert a a mailbot to a shared mailbox

Set-Mailbox ConfRoom1 -Type Shared

http://technet.microsoft.com/en-us/library/bb201749.aspx