BService Broker ships with the Workgroup, Standard, and Enterprise Edition of SQL Server 2005. But what if you want to deploy an application that uses Service Broker on SQL Server Express 2005?
Service Broker works just fine with SQL Express, with one caveat. That is, the SQL Express instance must connect to one (or more) of the non-SQL Express versions of SQL Server 2005 such as Workgroup, Standard and Enterprise Edition. So what does that mean? You cannot connect two SQL Express instances directly via Service Broker.
Hope this helps,