Proxy and WCF

[TonyValenti]

In current versions of .NET, will WCF communications be routed through fiddler if no proxy is specified and I open fiddler?

[mconnew]

For HTTP/HTTPS traffic, yes as long as the hostname isn't "localhost". You can use your actual machines name (run hostname at a command prompt if you don't know what it is) to connect to a service running locally and it will go through fiddler if it's configured as the system proxy.
This is presuming you are using all the binding defaults. If you change any of the proxy settings on the binding, then you'll get different behavior depending on what you changed.