PFADMIN is a nice utility and helping a lot to manage the permissions of of Exchange 2003 and 2007 – mailbox and calendar permissions. But it is not supporting to manage Exchange 2010 as Exchange 2010 no longer support support WebDAV.

Microsoft Power Shell commands are very helpful to check and manage the objects in Exchange 2010.

For example, the permissions for a calendar can be viewed using the “Get-MailboxFolderPermission” command, and permissions can be removed using the “Remove-MailboxFolderPermission” command.

To assign Limited Details access of a user calendar  for everyone in your organisation (let’s say you got a AllStaff distribution group),

Add-MailboxFolderPermission -Identity\calendar -User AllStaff -AccessRights LimitedDetails

More details from Microsoft: