SAC (Surface Are Configuration) was the great possibility to configure the SQL Server 2005, so there were some options to configure the DAC(Dedicated Admin Connection), using xp Store Procedures, CLR Integration, AdHoc remote Queries that enables the OPENROWSET & OPENDATASOURCE support, SQL Mail etc.
Now in SQL Server 2008 and SQL 2008 R2, you cannot find anymore the SAC as config tool! You can configure Surface Area via SSMS (SQL Server Management Studio) using the FACETS, that are located at the SQL Server Instance >> right click >> Facets as shown in the fig below:
Choose the correct Facets in our case the Surface Area Configuration. As you can see, you have lot of the Facets except the SAC Facets, that you can configure for the SQL Server.
At the first view all the features are disabled by default, so you have possibility to change the values for each feature from Flase to True, to activate them for your SQL Server. It is recommended, to enable only those features that you need, otherwise you will leave the possiblity for any potential attack!
Important thing here, is that you don't need to restart you database engine to affect the changes and you can use the button "Export Current State as Policy..." to export the current configuration then apply to the other SQL Server with the same Surface Area Configuration features.
On the other hand if you want to know more about the facets in SQL Server 2008 (R2), it would be better to visit this location.