Index: wp-includes/formatting.php
===================================================================
--- wp-includes/formatting.php	(revision 21850)
+++ wp-includes/formatting.php	(working copy)
@@ -2797,6 +2797,14 @@
 			$value = preg_replace('/[^a-zA-Z0-9_-]/', '', $value); // strips slashes
 			break;
 
+		case 'blog_public':
+			// This is the value if the settings checkbox is not checked on POST. Don't rely on this.
+			if ( null === $value )
+				$value = 1;
+			else
+				$value = intval( $value );
+			break;
+
 		case 'date_format':
 		case 'time_format':
 		case 'mailserver_url':
Index: wp-admin/options-reading.php
===================================================================
--- wp-admin/options-reading.php	(revision 21845)
+++ wp-admin/options-reading.php	(working copy)
@@ -142,15 +142,15 @@
 <td><fieldset><legend class="screen-reader-text"><span><?php has_action( 'blog_privacy_selector' ) ? _e( 'Site Visibility' ) : _e( 'Search Engine Visibility' ); ?> </span></legend>
 <?php if ( has_action( 'blog_privacy_selector' ) ) : ?>
 	<input id="blog-public" type="radio" name="blog_public" value="1" <?php checked('1', get_option('blog_public')); ?> />
-	<label for="blog-public"><?php _e( 'Allow search engines to index this site.' );?></label><br/>
+	<label for="blog-public"><?php _e( 'Allow search engines to index this site' );?></label><br/>
 	<input id="blog-norobots" type="radio" name="blog_public" value="0" <?php checked('0', get_option('blog_public')); ?> />
-	<label for="blog-norobots"><?php _e( 'Ask search engines not to index this site.' ); ?></label>
+	<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 else : ?>
-	<label for="blog_public"><input name="blog_public" type="checkbox" id="blog_public" value="1" <?php checked( '1', get_option( 'blog_public' ) ); ?> />
-	<?php _e( 'Allow search engines to index this site' ); ?>
-	<p class="description"><?php _e( 'It is up to search engines to honor a request to not index this site.' ); ?></p>
+	<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>
+	<p class="description"><?php _e( "It is up to search engines to honor this request." ); ?></p>
 <?php endif; ?>
 </fieldset></td>
 </tr>