From : http://blogs.technet.com/mdop/archive/2009/10/20/mdop-2009-r2-is-now-available.aspx
Don't know what MDOP is yet. MDOP employs six innovative technologies to increase desktop manageability, reduce TCO, and improve overall infrastructure satisfaction:
Microsoft Application Virtualization (App-V) turns applications into centrally managed services that are never installed, never conflict, and are streamed on demand to end users.
Microsoft Enterprise Desktop Virtualization (MED-V) provides deployment and management of virtual PC images to enable key enterprise scenarios, primarily resolving application compatibility with a new version of Windows.
Microsoft Advanced Group Policy Management (AGPM) enhances governance and control over Group Policy through robust change management, versioning, and role-based administration.
Microsoft Asset Inventory Service (AIS) is a hosted service that collects software inventory data and translates it into actionable business intelligence.
Microsoft Diagnostics and Recovery Toolset (DaRT) reduces downtime by accelerating troubleshooting, repair, and data recovery of unbootable Windows-based desktops.
Microsoft System Center Desktop Error Monitoring (DEM) provides insights into application and operating system failures, allowing helpdesk to be more proactive in managing PC problems, without installing an agent to the endpoint.
You can read one of the 44 MDOP case-studies at the Microsoft Case Study site.