Exchange 2010 ships with some powerful scripts for managing Public Folder Client Permissions.
These scripts only apply to servers running Exchange 2007 or Exchange 2010, you can not specify a server running older versions of Exchange Server, although the Public Folder hierarchy can still be on an Exchange 2003, in case you want to add additional replicas etc (see my previous post).
The scripts are located together with the Exchange binaries, under: C:Program FilesMicrosoftExchange ServerScripts.
The scripts recursively goes through and updates your public folders replicas for every public folder in a hierarchy that you specify.