SQL Service Broker

SQL Service Broker is a platform for building asynchronous, scalable database applications.

With Service Broker, internal or external processes can send and receive guaranteed, asynchronous messages by using extensions to Transact-SQL Data Manipulation Language (DML). 

Messages can be sent to a queue in the same database as the sender, to another database in the same SQL Server instance, or to another SQL Server instance either on the same server or on a remote server.

An Introduction to SQL Server Service Broker (microsoft)

http://msdn.microsoft.com/en-us/library/ms345108(v=sql.90).aspx

SQL SERVER – Intorduction to Service Broker and Sample Script

http://blog.sqlauthority.com/2009/09/21/sql-server-intorduction-to-service-broker-and-sample-script/