Although I did reply to your question by email, I will post my response on here as well for others looking for answers to your question.
Currently, there are no plans to implement a printing feature with the Xceed DataGrid for Silverlight. Our next update will be for setting up the version 2.0 of the component which will increase the performance of the overall DataGrid. Although, I did find an article online which implements a printing feature at the click of a button. The author has a Live sample that you can see for yourself if you would like to incorporate that into your project. This feature has not been tested with the Xceed DataGrid for Silverlight.
Developer in Technical Support
Xceed - Multi-talented components - http://xceed.com