I actually discussed the issue of using WCF in SQL CLR with some members of the SQLCAT team and Microsoft this past week since it seems to becoming more popular for people to attempt, and I have yet to see where someone actually succeeded in anything but the most simplistic service call which did absolutely nothing. WCF was not considered a valid SQLCLR implementation by anyone I spoke to, which is good to hear since that has been my stance on the subject since it was first broached on another forum earlier this year.

You have two other options that are better for a number of reasons. First you can look at the External Activator for Service Broker in SQL Server 2008 which is an additional download you can use. In SQL 2005, you can hack together a SqlDependency if you are trying to make data change based calls to the service, and let the service run a watcher against SQL Server data and changes to the data trigger events in the service to bring it alive for processing.

The other option is to go to BizTalk, which by the way was designed and intended to do multi-service/SOA integration between your systems like you are trying to do. You need to expand your toolset and use the correct tools to solve the problem.