Is there anything Carol Bailey doesn't know about certificates and Configuration Manager? Doesn't seem like it as the Configuration Manager Team Blog has another great post on how to renew the Site Server Signing Certificate using Microsoft Certificate Services:
Have you tried to renew the existing site server signing certificate for a native mode site, and wondered how to do this without creating a new certificate? This post provides a procedure to do this that is suitable for when the site server is on either Windows Server 2003 or Windows Server 2008, and your PKI uses Microsoft Certificate Services.
J.C. Hornbeck | Manageability Knowledge Engineer