On SitePoint.com in the Server-side Coding blog there's a new tutorial that looks to help developers just wanting to get their feet wet with Silverlight to get started. Jordan Knight shows you how to build a simple applications using a combination of C# frontend and a PHP-powered backend.
You might think that it would be more difficult to use Silverlight in a PHP application, but it's actually quite simple; you can leverage JSON, XML, or any number of communication technologies to pass data from Silverlight to the PHP backend. However, in this article, we're choosing to go with a SOAP Web Service. I'll first show you how to start developing with Silverlight, then cover how you set up the web service in PHP, and finally demonstrate how to access the service from your Silverlight application.
You'll also need to have the Silverlight Tools and Visual Studio installed as well to be able to follow along. He walks you through the creation of a sample project, setting up the basic Silverlight app, making a WSDL for the SOAP service and making the sample web service with PHP's built-in SOAP functionality. With that in place, he shows how to consume the service with the C# frontend and how to send a sample message back out to the application.