Silverlight 2 Networking Options
http://weblogs.asp.net/dwahlin/archive/2008/04/10/silverlight-2-networking-options.aspx
Pushing Data to a Silverlight Client with a WCF Duplex Service - Part I
http://weblogs.asp.net/dwahlin/archive/2008/06/16/pushing-data-to-a-silverlight-client-with-wcf-duplex-service-part-i.aspx
Pushing Data to a Silverlight Client with a WCF Duplex Service - Part II
http://weblogs.asp.net/dwahlin/archive/2008/06/19/pushing-data-to-a-silverlight-client-with-a-wcf-duplex-service-part-ii.aspx