In the Windows 8 consumer preview and Server beta, IE10 and all other Microsoft WebSocket client and server features now support the final version of the IETF WebSocket Protocol. In addition, IE10 implements the W3C WebSocket API Candidate Recommendation. An article on the IE team blog explains this in much more detail.
Meanwhile, ASP.NET Developers can start using the System.Web.WebSockets library introduced in .NET Framework 4.5 to leverage this technology. Note that this is different from the System.Net.WebSockets namespace which contains the actual implementation of the WebSocket standard in .NET – System.Web.WebSockets provides the integration of this implementation with ASP.NET.
WebSocket is a technology for providing bi-directional communication channels over a single TCP socket. This is a much simpler alternative to using Comet Channels to allow the web server to push data to a web client, without the client explicitly requesting it. Although the technology itself has been available since much earlier (Google Chrome first announced support for it in late 2009), it finally became a Proposed Standard last December essentially receiving a nod from the Internet Engineering Task Force.