Okay, I have looked everywhere on this site re: pings. And everyone claims that WordPress, as a default, sends out a ping everytime you do a post edit.
What I haven't seen is anyone as this:
Under discussion, you have the choice to check off this box
Allow trackbacks and pingbacks on this page.
If this is unchecked, does it still send them out? If that's the case, I can then see installing one of the plugins suggested.