Index: src/wp-signup.php
===================================================================
--- src/wp-signup.php	(revision 35418)
+++ src/wp-signup.php	(working copy)
@@ -69,6 +69,9 @@
 		.mu_register label { font-weight:700; font-size:15px; display:block; margin:10px 0; }
 		.mu_register label.checkbox { display:inline; }
 		.mu_register .mu_alert { font-weight:700; padding:10px; color:#333333; background:#ffffe0; border:1px solid #e6db55; }
+		.mu_register fieldset { border:0; padding:0; margin:0; }
+		.mu_register input[type="checkbox"] { vertical-align:middle; }
+		.mu_register p.description { margin-top:0.2em; font-size:small; font-style:italic; }
 	</style>
 	<?php
 }
@@ -163,18 +166,34 @@
 
 	<div id="privacy">
         <p class="privacy-intro">
-            <label for="blog_public_on"><?php _e('Privacy:') ?></label>
-            <?php _e( 'Allow search engines to index this site.' ); ?>
-            <br style="clear:both" />
-            <label class="checkbox" for="blog_public_on">
-                <input type="radio" id="blog_public_on" name="blog_public" value="1" <?php if ( !isset( $_POST['blog_public'] ) || $_POST['blog_public'] == '1' ) { ?>checked="checked"<?php } ?> />
-                <strong><?php _e( 'Yes' ); ?></strong>
-            </label>
-            <label class="checkbox" for="blog_public_off">
-                <input type="radio" id="blog_public_off" name="blog_public" value="0" <?php if ( isset( $_POST['blog_public'] ) && $_POST['blog_public'] == '0' ) { ?>checked="checked"<?php } ?> />
-                <strong><?php _e( 'No' ); ?></strong>
-            </label>
-        </p>
+			<fieldset>
+				<label><?php has_action( 'blog_privacy_selector' ) ? _e( 'Site Visibility' ) : _e( 'Search Engine Visibility' ); ?></label>
+				<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' ) ) : ?>
+					<label for="blog-public">
+						<input id="blog-public" type="radio" name="blog_public" value="1" <?php checked('1', get_option('blog_public')); ?> />
+						<?php _e( 'Allow search engines to index this site' ); ?>
+					</label>
+					<label for="blog-norobots">
+						<input id="blog-norobots" type="radio" name="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( 'Note: Neither of these options blocks access to your site &mdash; it is up to search engines to honor your request.' ); ?></p>
+					<?php
+					/** This action is documented in wp-admin/options-reading.php */
+					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>
+					<p class="description"><?php _e( 'It is up to search engines to honor this request.' ); ?></p>
+				<?php endif; ?>
+			</fieldset>
+		</p>
 	</div>
 
 	<?php