With all new 4.0 releases the Entity Framework is heard to be mature enough with it's new POCO support.
This article walks through the use of the POCO features of EF4 as well as some good design aspects; Repositiories, ViewdataModels, Automapping, Repositories with POCOs separated from EF, Dependency Injection.
What I still miss is a good description on implementing Fake (Mock) Repositories when the structures are more real world and not just a list of whatever. In reality there are a lot more relations/navigations between the objects.
Anyway, the article, in Swedish, is at this URL;
Read it for a good walk-through on a solid design.