If you ever need to deploy a WCF service to SharePoint 2007, there's plenty of information about how to do it on the web. Including how to make it work with Integrated Authentication or Forms Authentication. And it's all great and works. However, I had to make the service "run" under the context of a particular web (which was actually a subweb). By this I mean that if I have a root site and a subsite and my WCF service calls SPContext.Current.Web I'd want it to return the subsite, not the root site....