Here is an overview of the SQL Server Resource Governor in slides and some demos.
SQL Server 2008 provides Resource Governor, a feature than you can use to manage SQL Server workload and system resource consumption. Resource Governor enables you to specify limits on the amount of CPU and memory that incoming application requests can use.
Resource Governor is configurable in SQL Server Management Studio by using Transact-SQL statements or by using Object Explorer.
Resource Governor is available only on the Enterprise, Developer, and Evaluation editions of SQL Server.