We had a new System Center Virtual Machine Manager 2008 Knowledge Base article published last week.  This one discusses an issue where a read only domain controller (RODC) can only be used as a Host if it was already a Host prior to being promoted.  The link and title is below:

KB975113 - Using a Read Only Domain Controller as a Host in SCVMM 2008


J.C. Hornbeck | Manageability Knowledge Engineer