LINQ to SQL multi-tier design?

I want to beging learning LINQ to SQL and want to create a project. I am a little confused about what I have been reading about LINQ to SQL. It is my understanding that LINQ to SQL will act as my DAL. Would I still need a BLL in my LINQ to SQL app? I thought that the Entities are created that represent the database tables and properties. If I use a BLL, would I have to create objects with state (properties) in this BLL or would my BLL simply contain methods that call my DAL methods/queries using LINQ? I was reading a tutorial created by Ferdy who developed Blogo.NET and he used a BLL with properties that created object state. At the same time though, I don't see why you would duplicate object properties that are created when you create your Entities with LINQ. Any thoughts?
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