Index: wp-admin/update-core.php
===================================================================
--- wp-admin/update-core.php	(revision 17625)
+++ wp-admin/update-core.php	(working copy)
@@ -139,6 +139,9 @@
 	echo ' &nbsp; <a class="button" href="' . esc_url( self_admin_url('update-core.php') ) . '">' . __( 'Check Again' ) . '</a>';
 	echo '</p>';
 
+	if ( is_dir( ABSPATH . '.svn' ) )
+		echo '<div class="updated inline"><p>' . __( '<strong>Warning:</strong> It appears that you are running a Subversion checkout of WordPress. You may wish to keep WordPress up to date using Subversion instead of the auto-updater.' ) . '</p></div>';
+		
 	if ( !isset($updates[0]->response) || 'latest' == $updates[0]->response ) {
 		echo '<h3>';
 		_e('You have the latest version of WordPress.');