The switch from a polling architecture to a notification one greatly reduces the amount of over the wire traffic that has to take place. Consider the case of a

The switch from a polling architecture to a notification one greatly reduces the amount of over the wire traffic that has to take place. Consider the case of a blog where it's not updated for a month: every feed reader continues to continuously poll for the feed every hour of every day (though some are better about setting a timing decay, just checking for header last changed, etc.). With PubSubHub the traffic sent is 0. Some other things to consider: 1. The obvious case for this is blogs, but PubSubHub can be the foundation of other more interesting and new projects: consider a distributed Twitter like micro blogging service. I'm not saying building one is a good idea, just that it would be better built on PSH than polling. 2. People are lazy and feeds put in feedreaders are polled forever. I've worked on multiple systems where years later feed readers are still checking every hour for feeds that are missing, or just completely irrelevant.