Taken from Silverlight (specifically this port),
TransitioningContentControl is great for switching content smoothly around.
At it’s core,
TransitioningContentControl is a
ContentControl, so only one child element can be displayed at a time.
When you change the content, an animation is played switching the two.
<Controls:TransitioningContentControl x:Name="transitioning" Width="150" Height="50" Transition="DownTransition" />
Built in there are several transitions: