There is also another way to easily add easing in the code behind. Check out Artefact Animator – http://artefactanimator.codeplex.com/. It doesn’t use storyboards but it gives you a simple syntax that mimics Tweener for Flash. It also uses the same code for the Silverlight and WPF version.

For Example:

ArtefactAnimator.AddEase (element, Canvas.LeftProperty, 250, .7, AnimationTransitions.CubicEaseOut, 0);