Not only IIS web server can host Silverlight applications. Apache can host up Silverlight content too. Silverlight introduces two new file extensions (.xaml for loose XAML files and .xap for the zip-based binary packaging format). As a result, you need to add the MIME types for those file extensions to your web server so that it recognizes Silverlight content appropriately. Here are the MIME types you need to add to the server configuration:
That’s all you have to do. IIS 7, included in Windows Server 2008, already includes all the relevant MIME types, including both .xap and .xaml extensions, so if you’re using Windows Server 2008, you’re all set.
If you want to add the relevant types to your web server to support WPF and ClickOnce applications also add next: