A sample that demonstrates how to implement Data Virtualization (or Stealth Paging) for Silverlight (could also be adapted for WPF). Includes a VirtualizingWrapPanel.
Original project from:
http://blog.functionalfun.net/2012/08/data-virtualization-in-silverlight.html
but I changed a lot of things so that it works with both, SL5 and WPF and Interlinq over WCF!