Index: wp-includes/link-template.php
===================================================================
--- wp-includes/link-template.php	(revision 7955)
+++ wp-includes/link-template.php	(working copy)
@@ -681,9 +681,13 @@
 }
 
 function next_posts($max_page = 0) {
-	echo clean_url(get_next_posts_page_link($max_page));
+	echo get_next_posts($max_page);
 }
 
+function get_next_posts($max_page = 0) {
+	return clean_url(get_next_posts_page_link($max_page));
+}
+
 function next_posts_link($label='Next Page »', $max_page=0) {
 	global $paged, $wp_query;
 	if ( !$max_page ) {
@@ -693,9 +697,10 @@
 		$paged = 1;
 	$nextpage = intval($paged) + 1;
 	if ( (! is_single()) && (empty($paged) || $nextpage <= $max_page) ) {
-		echo '<a href="';
-		next_posts($max_page);
-		echo '">'. preg_replace('/&([^#])(?![a-z]{1,8};)/', '&#038;$1', $label) .'</a>';
+		$result = '<a href="';
+		$result .= get_next_posts($max_page);
+		$result .= '">'. preg_replace('/&([^#])(?![a-z]{1,8};)/', '&#038;$1', $label) .'</a>';
+		echo apply_filters('next_posts_link', $result);
 	}
 }
 
@@ -711,15 +716,20 @@
 }
 
 function previous_posts() {
-	echo clean_url(get_previous_posts_page_link());
+	echo get_previous_posts();
 }
 
+function get_previous_posts() {
+	return clean_url(get_previous_posts_page_link());
+}
+
 function previous_posts_link($label='&laquo; Previous Page') {
 	global $paged;
 	if ( (!is_single())	&& ($paged > 1) ) {
-		echo '<a href="';
-		previous_posts();
-		echo '">'. preg_replace('/&([^#])(?![a-z]{1,8};)/', '&#038;$1', $label) .'</a>';
+		$result = '<a href="';
+		$result .= get_previous_posts();
+		$result .= '">'. preg_replace('/&([^#])(?![a-z]{1,8};)/', '&#038;$1', $label) .'</a>';
+		echo apply_filters('previous_posts_link', $result);
 	}
 }