Use Inversion of Control to decouple views and viewmodels in WPF.

In the WPF+Prism+Unity world (or Silverlight+Prism+Unity), an application begins with the Shell, which includes the user interface (a WPF window). That window displays one or more WPF User Controls.

With a bigger WPF user base it should mean that designers everywhere can help keep the user experience bar high and deliver some cool RIAs and start leveraging 3D more.