Travis Wright has just posted a brilliant video on the SCSM Engineering blog on how to use a workflow and a powershell script to modifiy an attribute in Active Directory based on a change in the CMDB in Service Manager.
http://blogs.technet.com/b/servicemanager/archive/2010/10/07/creating-an-ad-connector-to-update-ad-when-the-service-manager-cmdb-is-updated-using-powershell-and-workflow.aspx
The blog post concentrates on updating the Business Phone number in AD, but this is equally valid for any attribute on any change and not just for AD.