This KB now discusses support for installing an OpsMgr reporting server on a DC (if required, but not recommended) http://support.microsoft.com/kb/942862/en-us

Therefore the statement (Operations Manager 2007 does not support the installation of the Reporting Server on a computer that also functions as an Active Directory domain controller) here in the documentation is superceded http://technet.microsoft.com/en-us/library/bb309625.aspx 

 

INTRODUCTION

This article describes an extension in the support boundaries for the Reporting Server feature in Microsoft System Center Operations Manager 2007.

MORE INFORMATION

When System Center Operations Manager 2007 was released, this product did not support the installation of the Reporting Server feature on an Active Directory directory service domain controller. Additionally, the following information appeared under How to Deploy the Reporting Server Using the Setup Wizard in Operations Manager 2007 in System Center Operations Manager 2007 Online Help:

Operations Manager 2007 does not support the installation of the Reporting Server on a computer that also functions as an Active Directory domain controller.

This information is no longer true. We have tested the installation of Reporting Server on a domain controller. Also, we provide full support for the installation of the Reporting Server feature on a domain controller.