Curious what your Windows Phone 7 Start Screen will look like with your contacts and pictures? The Windows Phone Facebook page might help satisfy your curiousity.
Microsoft has put a Windows Phone 7 demo on their Facebook page that runs through the new system with generic contacts and pictures. But if you allow access, you can populate the demo Windows Phone with your Facebook pictures and contacts.
The demo is not interactive but gives you a decent feel for what to expect from your Windows Phone 7.