Using MEF and querying the catalog container with VB.NET

I am using the Managed Extensibility Framework preview 5 in VB.NET, and I have to say, that it rocks! The project I am writing is a UI container that has “add-ins” that process files and such. I am working with another programmer to develop other add-ins for the app as well. To query for specific metadata, we first have to create an interface and a custom attribute.