You can't manage what you can't see.  It's typically very difficult for those managing permissions within SharePoint to understand account and object permissions within their scope of authority across the farm.  In addition to the lack of permissions visibility in SharePoint, administrators oftentimes have a difficult time managing permissions. 

The security trimmed nature of DeliverPoint :Permissions offers a radical new approach to managing permissions in SharePoint, consistent with SharePoint's distributed architecture.  With DeliverPoint :Permissions, administrators of all levels can now easily discover and manage permissions across their scope of authority in the farm. 

• Built for administrators of all levels: central administrators, site collection administrators, and end-user administrators
• Central Administrators maintain control
• Discover, copy, transfer, and delete account and object permissions quickly and easily
• Keep the farm clean when employees leave the company or transfer divisions
• Empower non-IT administrators to manage permissions within their respective site collections, sites and workspaces
• Intuitive design
• Seamless integration with Microsoft Office SharePoint Server 2007 and Windows SharePoint Server 3.0.