Shared Folders are used to manage shared resources over a network. Users may specify folders to share with other computers on a network. All computers on the network, depending on settings, may view and possibly modify the shared folder's content.
Microsoft Exchange Server is a mail server, calendaring software and contact manager. It runs on Windows Server and it is one of the main elements present into a Microsoft infrastructure. It often happens that one of the first requirements of an identity manager project is to integrate Microsoft Exchange in order to manage, into the global/centralized user workflow, mailboxes and mail contacts as well.
Windows PowerShell is a command-line shell and scripting language designed especially for system administration. Its cmdlets let you manage computers and all server-side Microsoft applications (e.g. Exchange, SharePoint, FileServer, Active Directory, ...).
There are few years that I listen always the usual complains about the big mess caused by an uncorrect use of Active Directory groups in order to reflect own organization and manage access permissions to the resources.