IE's platform previews are simply minimal-chrome wrappers around the rendering engine. You'll need to wait until an IE 10 beta appears to find out what they've done to the UI.

You can move the tabs to be under the address bar. I prefer to squeeze them. Gives me an extra 15 or so pizels.

I am not a fan of this UI myself, but it is just a default. You can change this behavior by right clicking on the bar and checking the "Show tabs on a separate row" option.