Silverlight 5 Beta introduces a new ICustomTypeProvider interface that enables data binding to objects the structure of which cannot be known until runtime. This is a common problem when you work with data in any format from databases to metadata or XML
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Read the complete post at http://blogs.msdn.com/b/silverlight_sdk/archive/2011/04/25/binding-to-dynamic-properties-with-icustomtypeprovider-silverlight-5-beta.aspx