HTTP-Push (Comet/Reverse Ajax)using Silverlight to Javascript bridge?
You’ll have some serious scalability problems, and it’s a royal pain to implement. See: http://devgripes.wordpress.com/2009/11/14/pollingduplexhttpbinding-absolute-rubbish/ If you want a Bayeux implementation in Silverlight, you want WebSync. (Disclaimer: I work for Frozen Mountain Software)