After looking into the new features of WPF in .NET 3.5 SP1, I will highlight the new features for data access in this post.
In short, there were great improvements and additions to ADO.NET in the service pack. Specifically the introduction of the ADO.NET Entity Framework and Data Services in combination with the ADO.NET Entity Designer in Visual Studio are exciting features that are worthwhile a closer look.
ADO.NET Entity Framework
The ADO.NET Entity Framework is the next evolution of ADO.NET, raising the level of abstraction at which programmers work with data, and allowing the database structure or data source to evolve without significant impact to the application code.
Rather than coding against rows and columns, the ADO.NET Entity Framework allows the definition of a higher-level Entity Data Model over your relational data, and allows developers to then program in terms of this model. Developers get to deal with the data in the shapes that make sense for the application, and those shapes are expressed in a richer vocabulary that includes concepts like inheritance, complex types, and explicit relationships.
Use LINQ to Entities with the Entity Framework for queries that help create easy to maintain code that retrieves and works with strongly typed data objects or business entities.
Example of a Data Entity Model in Visual Studio 2008 SP1
ADO.NET Data Services
The Microsoft ADO.NET Data Services framework provides a first-class infrastructure for developing the next wave of dynamic internet applications by enabling data to be exposed as REST-based data services that can be consumed by client applications (ASP.NET, AJAX, Silverlight) in corporate networks and across the internet. Easily build applications using a comprehensive set of Microsoft .NET libraries and client components, accessing data through uniform URI syntax and using standard HTTP verbs to operate on the resource.
ADO.NET Data Services provides a framework to build data services for relational data sources, such as Microsoft SQL Server, MySQL, DB2, and Oracle, using the built-in support for the ADO.NET Entity Framework, or for non-relational data sources using the pluggable provider model.