One of the key differences between Microsoft’s .NET 3.0 full blown Windows Presentation Foundation (WPF) and the sub-set Silverlight (formally WPF/e) is that Silverlight doesn’t support true 3D support. (Flash is the same way… if you want the appearance of 3D in flash or Silverlight you have to fake it)
Here is a project that started over at CodePlex that uses that power of the .NET framework to convert / render (fake) WPF 3D over in Silverlight. nice!