From the last section (5.0 Deprecated Features) in the read me file
5.0 Deprecated Features
This section covers SQL Server 2005 features that are no longer included with SQL Server 2008.
5.1 SQL Server Notification Services Removed from SQL Server 2008
SQL Server Notification Services will not be included as a component of SQL Server 2008, but will continue to be supported as part of the SQL Server 2005 product support life-cycle. Moving forward, support for key notification scenarios will be incorporated into SQL Server Reporting Services. Existing Reporting Services functionality, such as data driven subscriptions, addresses some of the notification requirements. Features to support additional notification scenarios may be expected in future releases.
There you have it, no more Notification Services