Pinging
Pinging is the way a weblog (or blog) notifies a server that its content has been updated.
When a new post has been made to a blog (or an old post has been updated) the blogging software sends a message to a ping server to let it know that there's been an update. A simple wordpress blog can easily ping multiple servers everytime you update your blog.
By pinging http://weblogupdates.com/ your blog will be listed on our website.
Read more on Wikipedia about ping (blogging).