Does Facebook provide access to any real time APIs so that you can respond to events as soon as they happen? If not, what alternatives are there and what are their limitations? For example, if I use polling instead, will they limit my api calls? And if I try using RSS feeds, about how much delay can I expect? Or maybe it would be possible to receive and process email notifications (if I could convince a user to forward mail to another email address), as they seem to be dispatched pretty promptly?