MSDN Magazine articles:

The Entity Framework In Layered Architectures
http://msdn.microsoft.com/en-us/magazine/cc700340.aspx

Anti-Patterns To Avoid In N-Tier Applications
http://msdn.microsoft.com/en-us/magazine/dd882522.aspx

Entity Framework: N-Tier Application Patterns
http://msdn.microsoft.com/en-us/magazine/ee321569.aspx

Building N-Tier Apps with EF4
http://msdn.microsoft.com/en-us/magazine/ee335715.aspx

Entity Framework 4.0 and WCF Data Services 4.0 in Visual Studio 2010
http://msdn.microsoft.com/en-us/magazine/ee336128.aspx

Entity Framework Design blog:

Self-Tracking Entities in the Entity Framework
http://blogs.msdn.com/b/efdesign/archive/2009/03/24/self-tracking-entities-in-the-entity-framework.aspx

N-Tier Improvements for Entity Framework
http://blogs.msdn.com/b/efdesign/archive/2008/11/20/n-tier-improvements-for-entity-framework.aspx

Sample codes:

Building N-Tier Apps with EF4
http://code.msdn.microsoft.com/mag200911EF4

Entity Framework 4.0 and WCF Data Services 4.0 in Visual Studio 2010
http://code.msdn.microsoft.com/mag201004VSData

Other helpful blogs:

Updating data using Entity Framework in N-Tier and N-Layer Applications (short lived EF contexts) – (Part 1) (Cesar de la Torre)
http://blogs.msdn.com/b/cesardelatorre/archive/2008/09/04/updating-data-using-entity-framework-in-n-tier-and-n-layer-applications-short-lived-ef-contexts.aspx

Optimistic Concurrency Updates using Entity Framework in N-Tier and N-Layer Applications (Part 2) (Cesar de la Torre)
http://blogs.msdn.com/b/cesardelatorre/archive/2008/09/05/optimistic-concurrency-updates-using-entity-framework-in-n-tier-and-n-layer-applications-part-2.aspx

N-Tier Methods in Entity Framework 4 – Use with Care (Julie Lermain)
http://thedatafarm.com/blog/data-access/n-tier-methods-in-entity-framework-4-ndash-use-with-care/