In the WPF scenario, you would not be interfacing directly from WPF (i.e. xaml views) directly to your unmanaged C++. You would always want to wrap your C++ modules some sort of VB or C# managed wrapper. (You could theoretically use a Managed C++ wrapper, but you'd be mad to do this.) WPF needs thin View Models written in a .NET language at the very least. WPF shouldn't have any access directly to your unmanaged code, so the question is more "can .NET apps interface with unmanaged C++?" and the answer is yes, certainly.
http://msdn.microsoft.com/en-us/library/aa984739(v=VS.71).aspx
