I wrote a small WordPress plugin today to prevent these link elements from showing up in the header of my websites:
<link rel="EditURI" type="application/rsd+xml" title="RSD" href="WPURL/xmlrpc.php?rsd" />
<link rel="wlwmanifest" type="application/wlwmanifest+xml" href="WPURL/wp-includes/wlwmanifest.xml" />
The first of these link elements instruct blog clients where to find the WordPress XML-RPC interface via really simple discovery (RSD).
The second tells Windows Live Writer where to find your WordPress administration dashboard, the location of the edit posts and manage comments scripts.
If you are not using any blog clients to log into your WordPress and make changes to your posts or approve comments, these is no reason to be publishing these script locations.
This plugin is now included in the official WP Plugins Directory.