Many services like Technorati, Feedster, Icerocket, Google Blog Search, and many others want a “ping” from you to know you’ve updated so they can index your content. In most blog software and blogging services you have to manually go to different websites to send let them know you’ve updated, and had a few questions from people who want to know if they have to do the same on WordPress.com. No, wordpress handle it all for us. When you post we send a ping to Ping-O-Matic – http://pingomatic.com – which then distributes it out to 15+ different services, all automatically. We want things to be as easy as possible for our users, so it’s another thing you just don’t have to worry about.