This module turns Nginx into an adept HTTP Push and Comet server. It
takes care of all the connection juggling, and exposes a simple
interface to broadcast messages to clients via plain old HTTP requests.
This lets one write live-updating asynchronous web applications as
easily as their oldschool classic counterparts, since the code does not
need to manage requests with delayed responses. The module implements a
no-frills publisher/subscriber protocol centered on uniquely
identifiable channels. It is an order of magnitude simpler and more
basic than similar protocols (such as Bayeux).

Read on, download, etc. at http://pushmodule.slact.net/

- Leo