I've setup my service according to the latest tutorials I've found, and everything seems to work fine.
HOWEVER,
In order to access the WebOperationContext.Current.IncomingRequest.UriTemplateMatch class which contains the QueryParameters collection (e.g. ?name=tom&age=20), I need to have the service configured to use WebHttpBehavior. The only way I've managed to get this to work is to self host it using WebServiceHost from a console application. I can't get it to work from the web.config or global.asax from IIS or cassini.
I find it strange that tutorials on how to use the web-api talk about IoC before hosting the thing in IIS: wouldn't that be far more useful? They all seem to use extremely simple services that don't use query strings at all, with IoC!
Here are the resources I've found that almost mention the problem but don't fix it:
You can do something like this:
http://localhost:12741/contact?name=George
yields: