From long time ago I write about how we can use Mole in layer isolation, for more info see the post here.
But with release of Visual Studio 11 Beta, it came with Microsoft Fakes, which I think it based on Moles, the main benfit of Microsoft Fakes or Moles the ability to mock or stub the sealed classes (no public constructors)
The Fakes framework helps developers create, maintain, and inject dummy implementations in their unit tests. The Fakes framework generates and maintains stub types and shim types for a system under test
Fore more information see the post on MSDN
To download Visual Studio and TFS 11 Beta click on the following link