The WordPress Comment Moderation Notifier http://www.howtogeek.com/howto/the-geek-blog/how-to-geek-software-wordpress-comment-moderation-notifier/
is a Windows app that notifies users about the number of comments in the moderation queue. It does this by requiring a plugin that adds an XML-RPC method called geek.getCommentModerationCount.
This seems like a helpful bit of information to expose, so I put together a patch against -trunk to implement this. It is basically the same code as the plugin with only a few modifications.
The included patch calls the method wp.getCommentModerationCount, other WordPress specific methods are under wp.* so this seemed like the best place for it. It also includes an alias for the geek.getCommentModerationCount method so that this app and others based on it will work unmodified.