A very useful question. I've learned something new. Policy-based management begins to look more useful.
But I guess MS must have changed their mind at some point but forgot to change BOL. The very first sentence in the Administering Servers by Using Policy-Based Management section (http://msdn.microsoft.com/en-us/library/bb510667.aspx) is
Policy-Based Management is a system for managing one or more instances of SQL Server 2008.
- and that was last updated as recently as November 2009.
Tom