Big problem on the client-side change. The new base class for proxies - XmlRpcClientProtocol - is derived from a .NET class - ClientProtocol. This works fine until you try to access an invalid URL when calling ClientProtocol's Send method. An exception is dumped to the console and the call to Send never returns. I guess this will have been fixed in beta 2 but for now it means I have to code my own version of ClientProtocol. Which is frustrating because ClientProtocol provides a lot of functionality.