Remote Desktop Services is the new name for Terminal Services.
Terminal Services has been around since NT4 and MS has made it better with each version of Windows.
It also forms the foundation Citrix XenApp is built on.
Speaking of XenApp, MS has added a bunch of features to RDS that look surprising like XenApp, but aren’t quite as useful…
With Server 2008 MS has added TS Gateways , which tunnel the RDP connection through HTTPS, to increase security. They have also added TS Farms, but they are limited in functionality and the RemoteApp feature which works similar to Application Publishing in XenApp – where you connect to the TS, but only get one application instead of the desktop.
RemoteApp/Application Publishing should not be confused with Application Virtualization. They are similar but differ in one key point, where the application gets it’s CPU cycles. Follow the link for to find out more.