I found it interesting that this is ostensibly a notifications API, and nowhere is there any way to actually get notifications except by polling. I definitely understand why a push notification API would be a bad idea, but is polling with Last-Modified really the state of the art in notification APIs? What if you want to find out almost instantly when an event occurs, and not just at the granularity of your poll interval? At the API level, what do people use for this? Comet-style long polling? WebSockets? pubsubhubbub?