Now it’s almost official:

[...]

We’re making significant investments in the Entity Framework such that as of .NET 4.0 the Entity Framework will be our recommended data access solution for LINQ to relational scenarios.  We are listening to customers regarding LINQ to SQL and will continue to evolve the product based on feedback we receive from the community as well.

Tim Mallalieu
Program Manager, LINQ to SQL and Entity Framework

http://blogs.msdn.com/adonet/archive/2008/10/29/update-on-linq-to-sql-and-linq-to-entities-roadmap.aspx