There are some key commandlets to use when using EMS to administer Public Folders in Exchange 2007. Here is a short list of useful commands

• For Public Folders
  • Get-publicfolder -recurse |fl name,replicas
• For System Folders
  • Get-public folder \non_ipm_subtree |fl name, replicas

To Move replicas to Exchange 2007

Moveallreplicas.ps1 –server<sourceserver> -newserver<destinationserver>

Note: Scripts are found at %SystemDrive%\Program Files\Microsoft\Exchange Server\Scripts. To run a script, type the following in the Exchange Management Shell:

[PS] C:\>cd $exscripts

[PS] C:\Program Files\Microsoft\Exchange Server\Scripts>.\Moveallreplicas.ps1

To add or remove a server from a public folder replica’s properties including subfolders you can use the following two scripts:
RemoveReplicaFromPFRecursive.ps1 –TopPubicFolder <\folder> –Server toRemove <servername>

AddReplicatoPFRecursive.ps1 –TopPulblicFolder <\folder> -ServerToAdd <servername>

For more information see this post: http://msexchangeteam.com/archive/2007/06/25/445429.aspx