From a JS perspective this means building scalable comet application is as easy as not sending a response immediately but rather doing that in a callback function whenever an event might happen. As long as there is only a single node, writing an event queue is also easy. Just use an object that maps queue-ids to listeners.
To give Node.js a try I ported the work I did to allow servers to subscribe to custom events on the client. It turned out to be really straight forward. Here is the result.