In this post Gill Cleeren explains how Silverlight 4’s data binding engine has been extended with a few options that in some cases can avoid forcing you to create a converter.
When using data binding in Silverlight, we often have to include one or more converters. A converter is a class that implements the IValueConverter interface. This class defines 2 methods, Convert and ConvertBack. Convert is applied when the data in the data binding action flows from source object to target control. A common use for converters is formatting a date value that comes from the database into a specific format or adding a currency symbol to a double value.