If you take a desktop and separate the data, the user settings, and the applications... what do you have left?
If you have a way to deliver the data, the user settings, and the apps... do you even need a desktop?
What is a desktop?
This website about is desktop virtualization. But really the "desktop" part of "desktop virtualization" is just to separate it from "server virtualization" or "storage virtualization." What's interesting about "desktop virtualization" is that the desktop doesn't actually do anything. The desktop is just a logical container that holds links to apps, user settings, and maybe data.
In the traditional Windows world, The Desktop is just a euphemism for "the Windows OS and its related components." So traditional "desktop virtualization" has really been "Windows client OS virtualization" or "a way to provide users will access to their Windows OS." But moving forward, if we can deliver web apps as links, Windows apps as remote seamless Windows, and non-Windows apps as native iOS/WebOS/Blackberry/Android/RIA apps, then why exactly do we need The Desktop? If we can connect users to their data via Dropbox or Box or MobileMe, why do we need The Desktop?
So application virtualization and delivering apps to users is important. Data virtualization and making sure users have access to their data is important. User profile virtualization and making sure users can maintain their own settings across devices is important. But desktop virtualization? Delivering desktops? That's so 2005. In 2011 the desktop doesn't actually do anything.