Qubes beta 1 released

Is it common to seek hardware assistance for keeping track of which software you run? I can understand it if you have a locked down environment with whitelisted software, but not for servers.

That trusted software of yours might have holes in it. And when an attacker successfully tricks that software into running his code, it'll be just as trusted as anything else. Just witness all those game consoles out there, they have a lot more elaborate protection than TXT but every single one has been hacked to run unsigned ("homebrew") code.