MVVM (Model-View-ViewModel) is the new mantra for designing XAML based applications. This is brought out to address the emerging change in the approach of seperation of presentation layer & its logic.
With widely adopted WPF and Silverlight, MVVM has become a mandatory pattern.
One of the good reads for MVVM are:
- WPF Apps With The Model-View-ViewModel Design
- Tales from the Smart Client
- Introduction to Model/View/ViewModel pattern for building WPF apps