RSSCloud and PubSubHubBub basically enable RSS Feeds to update in real time instead of periodically — and RSS Feeds are already installed on all modern blogs and content management systems on the web.

What does this mean?

Do you know how Twitter works in Real Time?  Whenever a person you follow posts an update to twitter it is immediately “pushed” to simultaneously update in every place where you might read it in “Real Time”.

This means that every blog on the internet is now capable of updating RSS Feed readers in real time, and has the potential to give everybody access to the content contained on the entire internet at the speed of a Twitter update.

From the technical side it means that instead of your feed reader having to periodically “poll” the content source to find any new updates, the content source has the power to host the update “in the cloud” and make it available almost instantaneously to anyone who may want to read / consume the content.

This is a huge paradigm shift in the flow of the internet and it will be extremely interesting to see how developers build new services to take advantage of this fact…

I don’t know about you but I just installed the RSSCloud WordPress Plugin and I am pretty excited. =)

Update:

Here is a more detailed description from the RSSCloud website:

Three sided-cloud 

There are three sides to the cloud:

1. The authoring tool. I edit and update a feed. It contains a <cloud> element that says how a subscriber should request to notification of updates.
2. The cloud. It is notified of an update, and then in turn notifies all subscribers.
3. The subscriber. A feed reader, aggregator, whatever — that subscribes to feeds that may or may not be part of a cloud.