Index: wp-includes/class-wp.php
===================================================================
--- wp-includes/class-wp.php	(revision 23200)
+++ wp-includes/class-wp.php	(working copy)
@@ -346,18 +346,20 @@
 						|| !empty($this->query_vars['attachment_id'])
 					)
 				)
-			)
+			) {
 				$wp_last_modified = mysql2date('D, d M Y H:i:s', get_lastcommentmodified('GMT'), 0).' GMT';
-			else
+			} else {
 				$wp_last_modified = mysql2date('D, d M Y H:i:s', get_lastpostmodified('GMT'), 0).' GMT';
+			}
 			$wp_etag = '"' . md5($wp_last_modified) . '"';
 			$headers['Last-Modified'] = $wp_last_modified;
 			$headers['ETag'] = $wp_etag;
 
 			// Support for Conditional GET
-			if (isset($_SERVER['HTTP_IF_NONE_MATCH']))
+			if ( isset($_SERVER['HTTP_IF_NONE_MATCH']) )
 				$client_etag = stripslashes(stripslashes($_SERVER['HTTP_IF_NONE_MATCH']));
-			else $client_etag = false;
+			else
+				$client_etag = false;
 
 			$client_last_modified = empty($_SERVER['HTTP_IF_MODIFIED_SINCE']) ? '' : trim($_SERVER['HTTP_IF_MODIFIED_SINCE']);
 			// If string is empty, return 0. If not, attempt to parse into a timestamp
@@ -378,12 +380,11 @@
 
 		if ( ! empty( $status ) )
 			status_header( $status );
-		foreach( (array) $headers as $name => $field_value )
+
+		foreach( (array) $headers as $name => $field_value ) {
 			@header("{$name}: {$field_value}");
+		}
 
-		if ( isset( $headers['Last-Modified'] ) && empty( $headers['Last-Modified'] ) && function_exists( 'header_remove' ) )
-			@header_remove( 'Last-Modified' );
-
 		if ( $exit_required )
 			exit();
 
Index: wp-includes/functions.php
===================================================================
--- wp-includes/functions.php	(revision 23200)
+++ wp-includes/functions.php	(working copy)
@@ -902,7 +902,6 @@
 function wp_get_nocache_headers() {
 	$headers = array(
 		'Expires' => 'Wed, 11 Jan 1984 05:00:00 GMT',
-		'Last-Modified' => '',
 		'Cache-Control' => 'no-cache, must-revalidate, max-age=0',
 		'Pragma' => 'no-cache',
 	);
@@ -926,8 +925,6 @@
 	$headers = wp_get_nocache_headers();
 	foreach( $headers as $name => $field_value )
 		@header("{$name}: {$field_value}");
-	if ( empty( $headers['Last-Modified'] ) && function_exists( 'header_remove' ) )
-		@header_remove( 'Last-Modified' );
 }
 
 /**