I was working on my siverlight TFSTool project and I ran into the following problem. I have a WCF service that sits between the Silverlight (UI) and Team Foundation Server (backend), and every time the TFS throws an exception I would catch it and throw it to the UI but for some reason when I catch the exception in the UI I always get this "The remote server returned an unexpected response (404) Not Found" error message, even after I set "includeExceptionDetailInFaults" to true, which obviously is not very helpful since I want the user to know exactly why TFS failed. I tried to Google the problem and found some alternative ways to handle WCF errors in Silverlight:
http://silverlight.net/forums/t/18885.aspx
What I ended up doing is creating a custom exception object and pass that to the client as an out parameter. This works fine but I wonder if there's a better way of doing this, if you know a different approach, I would be very interested to know :-)