They will push del.icio.us bookmark events to subscribers in near real-time based on user (actor) or tag filters. Subscribers can also poll for events up to 60 minutes ago. I don’t think they have del.icio.us tagging events yet.

They also offer public actions from other providers, such as flickr, digg, twitter and others.

Unfortunately it needs your credentials for the services you want to orchestrate – most of them do not support Oauth (yet).

(BTW John I commented this yesterday as well but my comment never got out of the spam/moderation queue – I hope it will now)

Indeed you can, way more than is commonly appreciated. But there’s no practical way to subscribe to near-realtime notification of events in del.icio.us or other services.

I actually like Roy’s idea a lot. No new protocols, just highly efficient representations of events that anybody can fetch and analyze.

Agreed. On this point, I love this Roy Fielding article:

http://roy.gbiv.com/untangled/2008/paper-tigers-and-hidden-dragons

Pushing back against the prevalent notion that REST-style polling fails for large-scale event notification, he shows how appropriate resource design — e.g. a bitmap representation of the global state of all Flickr accounts — would enable producers and consumers to share the work in a smart way.

I like the “event topic” model, but wonder if it wouldn’t get stalled on trying to articulate an event model? I’ve kind of thought you could drive a lot of things just from del.icio.us bookmarks with smart tagging strategies.