As you may have read on my blog I have added an animation to the gear example  from Mike Harsh. Now, the gear community is here! Read Bryant Likes's Blog  post about the gears:
First the SDK team created an article about generating reflections in WPF/E . Then today I read via [Mike Harsh ] about Michael Schwarz  extending the example to include an animation . I also read in Mike's post about the WPF/E google group  (joined!) and in the group I read Dave Campbell 's post about extending the example further to roll the gear across the screen . I couldn't help myself and I took it one step further and gave the rolling motion a little twist so that it looks like the wheel accelerates and hits a wall.
Read the full post about the extended example... 
What comes next with the gear example? Mike, thank you for your initial example... ;)