Index: src/wp-admin/options-reading.php
===================================================================
--- src/wp-admin/options-reading.php	(revision 25653)
+++ src/wp-admin/options-reading.php	(working copy)
@@ -150,7 +150,22 @@
 	<input id="blog-norobots" type="radio" name="blog_public" value="0" <?php checked('0', get_option('blog_public')); ?> />
 	<label for="blog-norobots"><?php _e( 'Discourage search engines from indexing this site' ); ?></label>
 	<p class="description"><?php _e( 'Note: Neither of these options blocks access to your site &mdash; it is up to search engines to honor your request.' ); ?></p>
-	<?php do_action('blog_privacy_selector'); ?>
+	<?php 
+	/**
+	 * Enable the legacy 'Site Visibility' privacy options.
+	 *
+	 * By default the privacy options form displays a single checkbox to 'discourage' search
+	 * engines from indexing the site. Hooking to this action serves a dual purpose:
+	 * 1. Disable the single checkbox in favor of a multiple-choice list of radio buttons.
+	 * 2. Open the door to adding additional radio button choices to the list.
+	 *
+	 * Hooking to this action also converts the 'Search Engine Visibility' heading to the more
+	 * open-ended 'Site Visibility' heading.
+	 *
+	 * @since 2.1.0
+	 */
+	do_action( 'blog_privacy_selector' );
+	?>
 <?php else : ?>
 	<label for="blog_public"><input name="blog_public" type="checkbox" id="blog_public" value="0" <?php checked( '0', get_option( 'blog_public' ) ); ?> />
 	<?php _e( 'Discourage search engines from indexing this site' ); ?></label>