If you are interested in coding an AJAX client application that consumes asynchronous data notifications from a WCF backend service using the Microsoft Silverlight 3 HTTP polling duplex channel, check out the AJAX client for HTTP polling duplex sample. It contains a JavaScript library with client side implementation of the polling duplex protocol implemented in the PollingDuplexHttpBinding from Microsoft Silverlight 3. It has been tested with Internet Explorer 8, Firefox 3.5, and Chrome 2.0. Let us know what you think.

Tomasz Janczuk
Development Manager
WCF Team