With .NET 4.0 a lot of new features and technologies will see the light, as long as others will get improved, and Entity Framework will be one of those technologies that will get improved. A lot of this changes are being made...
Entity Framework has suffered great changes and in order to know more about them I recommend the following reading: POCO ( P lain O ld C LR O bject or Persistence ) in the Entity Framework 4.0 Sneak Preview: Persistence Ignorance and POCO in Entity Framework...