Index: wp-admin/includes/upgrade.php
===================================================================
--- wp-admin/includes/upgrade.php	(revision 11001)
+++ wp-admin/includes/upgrade.php	(working copy)
@@ -69,6 +69,9 @@
 
 	wp_install_defaults($user_id);
 
+	if ( got_mod_rewrite() && is_file(ABSPATH . '.htaccess') && is_writable(ABSPATH . '.htaccess') )
+		$wp_rewrite->set_permalink_structure('/%year%/%monthnum%/%day%/%postname%/');
+	
 	$wp_rewrite->flush_rules();
 
 	wp_new_blog_notification($blog_title, $guessurl, $user_id, $random_password);