Presentation virtualization involves separating an application's user interface from it's logic and presenting this user interface in a different location to where the application logic is being processed.
This seperation allows the application to be presented in one location whilst the applications deployment, configuration and maintenance can be done in another location.
Typically using this technology, applications are deployed in centrally located servers in data centres and using a remote display protocol the application user interface is presented to the user's device.
The user interacts with the user interface oblivious to the fact the application is actually running that is being processed at a different location and the user interface is merely relaying the user's keystrokes and mouse movements to the server where the application is running.
In return the server running the application, updates the user interface by sending updated refreshed user interface screen images to the client device.
Microsoft Terminal Services provides the engine for Windows based terminal server based installations.
In the latest edition of Windows 2008, Terminal Services has been renamed to Remote Desktop Services (RDS) and is Microsoft's implementation of thin client computing, where Windows applications and even entire desktops can be made accessible to a client device remotely.
Citrix XenApp, formerly Presentation Server, provides enhanced functionality and delivery mechanisms to the underlying Windows Terminal Services.
There is also the Linux Terminal Server Project which aims to provide a free open source thin client experience.