When WebSockets make their debug for .NET (Windows 8 and .NET 4.5), you will be able to persist a channel between the browser and the webserver, and the webserver will be able to feed the page live updates, etc.
In the meantime, if you want to update the page, the out-of-the-box way to do it is through polling. In DevDash, the status page checks the server every several seconds for the latest node statuses.
SignalR provides a better way to do this (as do other products that the SignalR links refer to). It achieves live updates by LONG POLLING. The page basically makes a request for a resource on the web server, and that resource blocks until there is something to respond with. As soon as there is something to respond with, the page receives the data and can update automatically.
I don’t have any hands on experience with this, but it reads great. There are several places in DevDash where I can use this.
It also has built in support for WebSockets if the browser and server supports it. That will allow you to use the same SignalR api via the websocket rather than via long polling.