I am sorry but you guys don't get it. Its not virtualization that is attractive it is Intel TXT. But TXT requires virtualization to do its thing.
The point of TXT is to allow you to create a measured (aka hashed via TPM) hypervisor that can protect itself even from the OS that launches it. But the main thing is it moves the root of trust. Under old style Trusted Computing (TC) you had to trust the BIOS of the your computer and no one in their right mind should trust that thing. But with TXT all you have to trust is Intel as the new root of trust is not your BIOS but is instead the AC module that Intel publishes over at the tboot project.
The point is that you can't build a trusted software stack using a classic operating system model without rewriting everything from scratch. But with TXT you can create a means to migrate slowly over time to a trusted and verified software stack.
So this whole "Security through Virtualization" is not about the isolation that it provides but about providing a migration path to a system where you can actually tell what software is running on your system.
I recommend you read the origional post about Qubes to understand the motivation and maybe pick up a copy of "Dynamics of a Trusted Platform" published by Intel Press.