Depends on what they are trying to accomplish.
Windows Server 2008 and Active Directory 2008 are supported.
RODCs should be treated as writable DCs as far as backup is concerned, However, Active Directory objects, forests, and domains cannot be recovered from an RODC backup.
Just make sure they're doing system state backups. If the RODC fails for any reason, they'll still need to recover it the same way as any other DC. If the forest, a domain, or an object corrupts, recovery will have to be done on a writable DC from its backup.