Read original post by Shawn Kendrot at Visually Located Blog
One of the most known page transitions on Windows Phone is the feather (or staggered item) transition. This is the transition you see when opening the mail app and the messages feather, or stagger in. This animation is also seen on the home page on the phone when the tiles stagger in. You usually see this transition whenever there is a list of items shown by any of the built in apps. This transition was previously only available through toolkits like the Windows Phone Toolkit or Telerik’s toolkit. Now this transition is available out of the box for Windows Phone Runtime apps.