In a MS KB324606 Article posted yesterday, Microsoft shows us a new tool, but don't try to use it in production if there are more than one DC.
Legacydn.exe is a tool that you can use to perform the following tasks:
Note Microsoft only supports using the Legacydn tool in a lab environment. The tool works only in a single domain controller environment.
|•||Change the Microsoft Exchange 2000 Server or Microsoft Exchange Server 2003 organization name.|
|•||Change the administrative group names.|
|•||View the legacyExchangeDN values.|
|•||Change the legacyExchangeDN values.|