As I mention in a previous blog post of mine, the method used to configure the MRSProxy service in Exchange 2010 changes when Exchange 2010 SP2 is applied. Basically the MRSProxy configuration are now stored in Active Directory instead of in a local web.config file on one or more CAS servers.
When you apply Exchange 2010 SP2 and then create a remote move request, you will get an error telling you that the Mailbox Replication service is disabled. This is because even though you enabled the MRSProxy service via the web.config file this configuration is no longer respected. Instead you must enable it using the following command so that it’s stored in Active Directory:
Set-WebServicesVirtualDirectory "<servername>\EWS (Default Web Site)" -MRSProxyEnabled $true
A Microsoft KB article has also been released in order to explain this.
Technology Architect/Writer/MS Vendor
MCM: Exchange Server | MVP: Exchange Architecture