You can accomplish this with the TurnstileFeatherEffect from the Windows Phone Toolkit. Here is a complete sample page.
You accomplish this by adding the following transitions to your page
<toolkit:TransitionService.NavigationInTransition>
<toolkit:NavigationInTransition>
<toolkit:NavigationInTransition.Backward>
<toolkit:TurnstileFeatherTransition Mode="BackwardIn"/>
</toolkit:NavigationInTransition.Backward>
<toolkit:NavigationInTransition.Forward>
<toolkit:TurnstileFeatherTransition Mode="ForwardIn"/>
</toolkit:NavigationInTransition.Forward>
</toolkit:NavigationInTransition>
</toolkit:TransitionService.NavigationInTransition>
<toolkit:TransitionService.NavigationOutTransition>
<toolkit:NavigationOutTransition>
<toolkit:NavigationOutTransition.Backward>
<toolkit:TurnstileFeatherTransition Mode="BackwardOut"/>
</toolkit:NavigationOutTransition.Backward>
<toolkit:NavigationOutTransition.Forward>
<toolkit:TurnstileFeatherTransition Mode="ForwardOut"/>
</toolkit:NavigationOutTransition.Forward>
</toolkit:NavigationOutTransition>
</toolkit:TransitionService.NavigationOutTransition>
And then state in which order you want them to fly in. You do this by setting the FeatheringIndex on each item that you want animated. If you have a ListBox that you want to animate the items, you only need to set the index on the ListBox itself and not on the DataTemplate.
<ListBox toolkit:TurnstileFeatherEffect.FeatheringIndex="0">
</ListBox>