The previous post explained what I mean by "Basic Back-End Services".
If you look at Silverlight 1.1 Alpha (or at the September Refresh of the Alpha release), you will see that it has a way of creating such services. A code sample can be found here. The idea is that you create a service just like you would create an ASP.NET AJAX service, then create a proxy using the slwsdl.exe tool, and then use the proxy to talk to your service.
However, what you see in the Alpha is a temporary solution. The main purpose of it was to show that service consumption is possible in 1.1, but the eventual solution will look different. If you are doing anything with services in 1.1, I urge you read future posts on this blog to find out what will change.