Will RT apps run on x86?

I was wondering if the metro apps that Microsoft is wanting people to write to run on ARM will run on x86? I wouldn't think so, but then I wondered what the plan is. I know RT isn't backwards compatible with legacy software, but surely MS doesn't want developers to have to make two versions of their applications going forward, do they? MS is making office for RT....so this needs to be a separately maintained version? Or is that just for desktop, what about Metro apps specifically? I'm confused how this works out.