Standardisation of things is always good and everyone these days what some kind of pub/sub system getting them events.
Seems that the days of polling a service may be long behind us soon.
Its not set up for everyone but there are some big names that already have an implementation. MailChimp, PayPal and Github to name a few.
WebHooks is a lightweight HTTP pattern providing a simple pub/sub model for wiring together Web APIs and SaaS services. When an event happens in a service, a notification is sent in the form of an HTTP POST request to registered subscribers. The POST request contains information about the event which makes it possible for the receiver to act accordingly.