Notification Services - What for it is used?
Having a feature of Notification on the server happenings is add-on for every DBA, Notification Services for SQL server 2005 has got that advantage. Microsoft confirms that capitalizing on the Microsoft .NET Framework and SQL Server, Notification Services provides an easy-to-use programming model for generating and formatting notifications based on personal subscriptions. This device-independent architecture can accept event data from any source and securely deliver it to a variety of mobile devices, including personal digital assistants (PDAs), cellular telephones, and more.
It is a good alerting or alarming mechanism that a DBA can deploy on their environment to add a powerful application development model to build declarative applications for instant messaging and notifications for the alerts/warnings/errors, a pro-active approach. Notification Services requires Windows 2003 and SQL Server 2005 to take advantage of this scalability notifications. The Licensing is depending upon the SQL Server standard or enterprise edition deployment on your environment, but its better to contact the local Microsoft representative in this regard.
Look at the information about Notificaton Services in SQL Server 2005.
Even Microsoft uses this feature within their enterprise such as Project REAL deployed with this product and MSN portal uses the Notification Services when the user is opted to recieve alerts on few options on that portal.