XML-RPC ping on comment

I am a member of a blog aggregation site (for students at my university) which checks RSS feeds every so often and displays posts, however there is another section which displays recent comments on member sites. To interface with this, I have to send an XML-RPC ping when a comment is posted with the usual permalink etc. (this ping causes the site’s script to check the post for comments). Is there a plugin that will allow me to ping (one) specified XML-RPC URL when a comment is posted (and, preferably, when a moderated comment is approved as well)? I know its a long shot, but I haven’t found anything in my searches.