As part of our ongoing experimentation with the HTML5 WebSocket proposed standard for duplex communication between web browsers and servers, we have prototyped a WebSocket protocol implementation based on Microsoft technologies. The prototype consists of a WCF service and a Silverlight client with an HTML bridge to JavaScript implemented in jQuery. You can read more about it at http://tomasz.janczuk.org/2010/07/silverlight-html5-websocket-client-with.html. You can also check out a sample web chat application based on the prototype at http://40interop.epiq.msftlabs.com/html5/wsdemo.html. Read more: The .NET Endpoint