I'm just finishing up two client sites that include blogging functionality.
Each time a new post is created or modified, the blogging software attempts to send a ping to rpc.pingomatic.com and rpc.technorati.com - this takes up to a minute to complete. Actually, I think the requests are just timing out and fail silently.
Since I can't find any relevant documentation on either of the two sites, I have disabled that functionality. As a result, the blog post updates have now become instantaneous.
Am I right in thinking that the whole ordeal of pinging servers with new posts has become obsolete?