A couple things have prompted me to look at application virtualisation recently, some organisations looking to upgrade to Windows 7, but still relying on IE6 (yes, I know) and organisations having issues pushing out app upgrades or OS upgrades to their users. Abstracting the app away from the OS would be great.
I'll be having a look at a few of the technologies listed at http://en.wikipedia.org/wiki/Application_Virtualization, in particular Xenocode and ThinApp.