AARRGGHH!! Well after hours and hours I've finally figure out how to trace messages in the February CTP of WinFX/WCF/Indigo. The Windows Communication Foundation is great stuff with lots of power, but these breaking changes between releases have been killing me. It will be nice when it's finally gold! The bottom line is you need to declare your source name as "System.ServiceModel.MessageLogging" or nothing will log. No errors, WCF just doesn't think that anyone's listening. Awww. That sounds sad!
<configuration>
<system.diagnostics>
<sources>
<source name="System.ServiceModel.MessageLogging" switchValue="Verbose">
<listeners>
<add name="messages" type="System.Diagnostics.XmlWriterTraceListener" initializeData="C:\logs\messages.e2e" />
</listeners>
</source>
</sources>
</system.diagnostics>
<system.serviceModel>
<diagnostics>
<messageLogging logEntireMessage="true" logMessagesAtServiceLevel="true"
logMalformedMssages="true" logMessagesAtTransportLevel="true" />
</diagnostics>
... (bindings, client/service)
</system.serviceModel>
</configuration>
What a pain. For the record, if you have the switchValue attribute in the wrong case nothing will log either. I hope that this helps someone!