The WPF animation capabilities are powerful, but a bit opaque.  EID helps, although in its current pre-beta state it only unlocks so much of the system.  Animation begs for more abstraction and it was only a matter of time before someone did it.  Check out Brandon Furwangler's Animation Behaviors.  He has a long post on the forums about it including a pretty comprehensive code sample.   The gist of it is the ability to add the following kinds of syntax to any FrameworkElement:

<Rectangle my:AnimationBehaviorHost.LoadedBehavior="SlideInFromTop"           my:AnimationBehaviorHost.ClickBehavior="Jiggle"           my:AnimationBehaviorHost.UnloadedBehavior="SlideOutToBottom"        Width="200" Height="100" Fill="red" />

Nice!  I look forward to seeing where Brandon -- and the community at large -- takes this. He's looking for contributors and help.