Yes and this is great for developers. Develop once, run on phone, tablet and laptop/desktop.
Have we had that confirmed? I was hearing that compiling a WinRT application for phone and desktop was going to take tweaking and recompilation.
I do know that design tools like blend support multiple layout views for different screen shapes and orientations. I can't see how this would be different. Underneath if you write .Net code it'll run on both.
It's very rare that the situation isn't really "develop once, debug everywhere." You might as well promise me a perfect optimizing compiler while we're at it.
And even then, is the GUI actually appropriate for all of your deploy targets? Usually not.