Attached is the source code I used to demonstrate WebSockets and my slide-deck (in the Open Office .odp format as well as exported to .ppt) at the NBNUG meeting yesterday (10/19/10). Client.html is the HTML/Javascript client, Server.cs is the C# server that just needs to be compiled into a console app project, referencing Nugget.dll (source is here: http://nugget.codeplex.com/).
Presentation Materials WebSocketsPresentation.zip
UPDATE: When I presented on WebSockets for NBNUG a few months ago, someone asked if it was possible to host WebSockets using IIS. Microsoft just released a prototype demonstrating a WCF-based WebSockets application that is hosted in IIS. You can check that out here: http://jclaes.blogspot.com/2011/01/html5-installing-microsoft-websockets.html