Index: wp-includes/default-filters.php
===================================================================
--- wp-includes/default-filters.php	(revision 5443)
+++ wp-includes/default-filters.php	(working copy)
@@ -160,6 +160,7 @@
 add_action('wp_head', 'locale_stylesheet');
 add_action('publish_future_post', 'wp_publish_post', 10, 1);
 add_action('wp_head', 'noindex', 1);
+add_action( 'wp_head', 'link_rel_prev_next' );
 add_action('wp_head', 'wp_print_scripts');
 if(!defined('DOING_CRON'))
 	add_action('init', 'wp_cron');
Index: wp-includes/link-template.php
===================================================================
--- wp-includes/link-template.php	(revision 5443)
+++ wp-includes/link-template.php	(working copy)
@@ -352,8 +352,10 @@
 
 // Navigation links
 
-function get_previous_post($in_same_cat = false, $excluded_categories = '') {
-	global $post, $wpdb;
+function get_previous_post($in_same_cat = false, $excluded_categories = '', $id = 0) {
+	global $wpdb;
+	
+	$post = &get_post( $id );
 
 	if( !is_single() || is_attachment() )
 		return null;
@@ -389,8 +391,10 @@
 	return @$wpdb->get_row("SELECT ID, post_title FROM $wpdb->posts $join $where $sort");
 }
 
-function get_next_post($in_same_cat = false, $excluded_categories = '') {
-	global $post, $wpdb;
+function get_next_post($in_same_cat = false, $excluded_categories = '', $id = 0) {
+	global $wpdb;
+	
+	$post = &get_post( $id );
 
 	if( !is_single() || is_attachment() )
 		return null;
@@ -438,7 +442,7 @@
 		return;
 
 	$title = apply_filters('the_title', $post->post_title, $post);
-	$string = '<a href="'.get_permalink($post->ID).'">';
+	$string = '<a href="'.get_permalink($post->ID).'" rel="prev">';
 	$link = str_replace('%title', $title, $link);
 	$link = $pre . $string . $link . '</a>';
 
@@ -454,7 +458,7 @@
 		return;
 
 	$title = apply_filters('the_title', $post->post_title, $post);
-	$string = '<a href="'.get_permalink($post->ID).'">';
+	$string = '<a href="'.get_permalink($post->ID).'" rel="next">';
 	$link = str_replace('%title', $title, $link);
 	$link = $string . $link . '</a>';
 	$format = str_replace('%link', $link, $format);
@@ -607,4 +611,62 @@
 	}
 }
 
-?>
+function link_rel_prev_next( $id = 0 ) {
+	if ( !is_single() ) {
+		return;
+	}
+	
+	$prev_url = '';
+	$next_url = '';
+	
+	$post = get_post( $id );
+	setup_postdata( $post );
+	
+	global $multipage, $numpages, $pagenow, $page, $wp_rewrite;
+	
+	if ( $multipage ) {
+		global $numpages, $pagenow, $page;
+		
+		if ( $page == 1 ) {
+			if ( $prev_post = get_previous_post( false, '', $post->ID ) ) {
+				$prev_url = get_permalink( $prev_post->ID );
+			}
+		} else {
+			if ( !$wp_rewrite->using_permalinks() || $post->post_status == 'draft' ) {
+				$prev_url = add_query_arg( 'page', $page - 1, get_permalink() );
+			} else {
+				$prev_url = trailingslashit( get_permalink() ) . user_trailingslashit( $page - 1, 'single_paged' );
+			}
+		}
+		
+		if ( $page == $numpages ) {
+			if ( $next_post = get_next_post( false, '', $post->ID ) ) {
+				$next_url = get_permalink( $next_post->ID );
+			}
+		} else {
+			if ( !$wp_rewrite->using_permalinks() || $post->post_status == 'draft' ) {
+				$next_url = add_query_arg( 'page', $page + 1, get_permalink( $post->ID ) );
+			} else {
+				$next_url = trailingslashit( get_permalink() ) . user_trailingslashit( $page + 1, 'single_paged' );
+			}
+		}
+	} else {
+		if ( $prev_post = get_previous_post( false, '', $post->ID ) ) {
+			$prev_url = get_permalink( $prev_post->ID );
+		}
+		
+		if ( $next_post = get_next_post( false, '', $post->ID ) ) {
+			$next_url = get_permalink( $next_post->ID );
+		}
+	}
+	
+	if ( !empty( $prev_url ) ) {
+		printf( '<link rel="prev" href="%s" />' . "\n", $prev_url );
+	}
+	
+	if ( !empty( $next_url ) ) {
+		printf( '<link rel="next" href="%s" />' . "\n", $next_url );
+	}
+}			
+
+?>
\ No newline at end of file