[snprbob86]

"Running Windows as a standard user and/or Vista's UAC mechanism seems to provide the same functionality."

This isn't true under Windows. It's not true under Linux or OSX either.

Think of your software security boundaries as an onion. In the middle you have kernel mode, then system services, then the administrator user land, followed by a common user. Application virtualization adds one more layer to the onion. Not only are applications insulated from your system, but they are also insulated from other applications.

The ultimate model is much closer to that of a web browser with domain restrictions on cookies and the like. This is the next logical step in fighting malware.