WebSub/PubSubHubbub的作者是Matthias Pfefferle,目前有100,000+个有效安装。已经Tested with 5.4.1版本的wordpress。
This plugin is a simple way to let people know in real-time when your blog is updated. PubSubHubbub/WebSub is widely adopted and is used by Google Alerts and many other services. Subscription requests are relayed through hubs, which validate and verify the request. Hubs then distribute new and updated content to subscribers when it becomes available.
This plugin:

Sends realtime notifications when you update your blog
Supports multi-user installations (WordPress MU)
Supports multiple hubs
Supports all of the feed formats used by WordPress, not just ATOM and RSS2
Supports latest specs

PubSubHubbub Version 0.4
WebSub W3C Version

Announces which hubs you are using by adding declarations to your template header and Atom feed

By default this plugin will ping the following hubs:

Demo hub on Google App Engine

Please contact me if you operate a hub that you would like to be included as a default option.