I just wanted to follow up with this. Tim & I went back and forth with this offline and resolved this particular error. When you use WCF you have to configure what is called an "end point" (think URI, ex. http://www.zzzzzzzz.com/MyWCFSite). This can be configured in either the *.config file or programmatically. In Tim's web.config he had the endpoint address partially filled in. However, he was configuring it programmatically (which you would think would completely override the *.config file setting). What actually happens is that it suffixed his programmatic endpoint with what was configured in the *.config file. This caused the error he was seeing.

It sounds like a bad design in WCF, but from what I understand it's a design feature: you can use a relative address configured in the *.config file and then swap out the actual web address in code and WCF builds the full URI from both (so you wouldn't need code changes between dev. and production).