Tim Bray talks about Practical Transparency, or how to publish financials in such a way that every interested party may receive the information in a timely fashion. Regular Atom feeds are served using HTTP, which requires polling. This might introduce delays up to half an hour with regular news readers.
As one of the solutions he proposes Atom over XMPP, and refers to it as elegant but fancy. I would like to think of it to be very much like the services by major news providers they still call 'telex', at least over in here in The Netherlands. All subscribers (news papers, online news sites, broadcasters) to the telex get streams of news items, all plain-text. Atom over XMPP is a way to pass on structured news, including markup, meta data and enclosures in much the same fashion.
Atom over XMPP works using the publish-subscribe
XMPP enhancement protocol over a regular Jabber network. So what Tim
describes as a persistent connection, is really a some client
application connected to its home Jabber server, and that home server
is connected to the service hosting the publish-subscribe node(s) for
This should be pretty easy to deploy. Just set up a Jabber server, add a general publish-subscribe service like Idavoll, set up the node(s) and write a few lines of code to send out the publish requests. This is how I publish my blog to Mimír, too.