How realtime web frameworks work?

With the recent advances in the web technologies like Node.js, WebSockets and cloud computing we are moving towards the new design paradigm for web apps and lot of smart developers are leading the way with their cool new frameworks. Is the design of this new frameworks a completely new development in Computer Science or has it been done before in a different context? Are there any research/white papers they rely on ? on a related note, Are we reinventing X Windows on the Web ?