[pubsubhubbub](http://code.google.com/p/pubsubhubbub/) — I’m not kidding — is an actual existing thing. Yeah, I too would have killed to be a fly on the wall when they decided to call it that, but there you go. So let’s dissect this piece of art of a name:
* `pubsub`, i.e. pub/sub, i.e. [publish/subscribe](http://en.wikipedia.org/wiki/Publish/subscribe), which is a common pattern in, well, the world, where multiple parties _subscribe_ to one or more _publishers_, to receive notifications on updates.
* `hub`, is a center of communication, often used for efficiency purposes, like an [ethernet hub](http://en.wikipedia.org/wiki/Ethernet_hub).
* `bub`, you tell me. I haven’t a clue.
So what is it, really? It’s a _protocol_ to enable near real-time update notifications among pubsubhubbub-supporting parties. Whereas RSS and Atom feeds required polling to receive updates, pubsubhubbub pushes information to parties. Currently various Google properties are have pubsubhubbub-support, such as [Google Reader](http://www.google.com/reader) and [Google Buzz](http://buzz.google.com). So, when you install a [pubsubhubbub plug-in for a wordpress blog](http://en.blog.wordpress.com/2010/03/03/rub-a-dub-dub-in-the-pubsubhubbub/), like I have and I push the publish button on a post, it will almost instantaneously appear in all of your Google Readers and your Google Buzz, whereas before, it may have taken a few minutes or hours to appear.