The following technologies and categories have had new topics added or existing topics updated with significant changes in the 23 January 2009 release of SQL Server 2008 Books Online.
Getting Started: New and Updated Topics (23 January 2009)
Integration Services: New and Updated Topics (23 January 2009)
Database Engine: New and Updated Topics (23 January 2009)
Reporting Services: New and Updated Topics (23 January 2009)