Today I have updated the Deployment Guide for Operations Manager 2007 Reporting on Windows Server 2008. This was due to some confusion from those who downloaded the doc and were attempting to setup this configuration in their environment. I received a few e-mails and determined this needed to be addressed accordingly. Specifically I had verbiage in a paragraph in the section "Installing SQL Server 2005 with Service Pack 2" where I eluded to the fact installing SQL 2005 with Reporting Services should be performed using a slipstreamed version of SQL 2005 with SP2. I don't remember why I had that statement in this paragraph, but there is no technical reason from my experience why you cannot install SQL 2005 RTM and then apply Service Pack 2. It has worked fine for me on various occasions.
Thanks to those who have pointed this out and sorry that this caused any unnecessary confusion.
This updated version will also be uploaded on the http://www.opsmanjam.com site within a day or so.