SQL Server 2008 R2 is released on April 21st, 2010 and in parallel with this new release, now is available also the Books OnLine for SQL Server 2008 R2 that is the primary documentation for SQL Server. I think that the BOL for SQL Server is the nearest location for the end user, where you can find the beginning help how to work with lot of the new features and how to use them with some examples, except this, you have also the additional links that are related to that topic that you are looking for.
BOL for SQL Server includes some info like:
- Setup and upgrade instructions.
- Information about new features and backward compatibility.
- Conceptual descriptions of the technologies and features in SQL Server.Procedural topics describing how to use the various features in SQL Server.
- Tutorials that guide you through common tasks.
- Reference documentation for the graphical tools, command prompt utilities, programming languages, and application programming interfaces (APIs) that are supported by SQL Server.
- Descriptions of the sample databases and applications that are available with SQL Server.
For more details and download, you can check here.