Seems this is now in the current Steam beta. The whole Intel CPU thing is an added security feature on top of the regular bit, so you don't actually need it.
It seems nice, actually. You verify your email addy and Steam makes some sort of determination on what your PC is. If anyone (including you) tries to log in from another PC, you will get an email with an authorization code. So to steal someones account they would have to somehow get your Steam login info as well as access to your email account.
Thumbs up. Once its out of beta I'll be sure to set it up. They mention there will be other forms of secondary authentication, like the Intel CPU thing but who knows, they might make authenticators like Blizzard.