Entity framework in a layered architecture?

Question

Doing some experiments around WCF and Entity Framework. A couple of questions.

Option 1:

I understand that entity framework classes can be seria

Answer 1

It's a very bad idea to expose EF classes over WCF. Microsoft made some serious mistakes that prevent this from being a useful scenario. They've exposed the entities as data contrracts, but also the base classes of the entity, and for backward links, expose two copies of the link.

On the other hand, it appears that ADO.NET Data Services have some magic that allow something close to this to work. Read the SilverLight article in this month's MSDN Magazine for an example, from the client side, of using ADO.NET Data Services.