One of the things that's new (and long overdue) in the new Windows Phone is better control over how apps look and feel. By now we have a pretty good look at the whole "panoramic" theme going on, as content flows easily from east to west and back again.
How's that all being done? Microsoft spells it out in its Windows Phone Design and UI Interaction Guide. Think of it as a "how-to" for application developers. [pdf link]