Take a look at this interesting post of Adam Kinney on animating an object by using the FluidMotionBehavior of Expression Blend 4.
I’ve been explaining the concept of Fluid UI, as a means to animate discrete properties. The first example that comes to mind is the Visibility property of an element. Its either Visible or Collapsed, there is no way to interpolate between the two values. When you change the Visibility property between different VisualStates and check the “Use Fluid UI” button, rather than instantly disappearing, Fluid UI will animate the opacity and scale transform to provide a visual transition between the discrete values.