ADO.NET Entity Framework June 2007 CTP now available
As you might know via ADO.NET 3.5 MS is shipping the Entity Data Model (EDM). This model is heavily influenced by the entity/relationship idiom, incorporates entity inheritance, and may be mapped to both relational and programming language concepts.
You can test out this Entity Framework via Visual Studio Orcas.
Check here for more information about the funtionality of EDM as well as detailled installation instructions.