recursive 2

<?php

$list = array(
              array('page_id' => '3',
                    'url' => '/johtamisjarjestelma/yritys',
                    'title' => 'Yritys'),
              array(
                    'page_id' =>  '4',
                    'url' =>  '/johtamisjarjestelma/yritys/historia',
                    'title' =>  'Historia'),
              array(
                    'page_id' =>  '5',
                    'url' =>  '/johtamisjarjestelma/testing',
                    'title' =>  'Testing'),
              array(
                    'page_id' =>  '6',
                    'url' =>  '/johtamisjarjestelma/testing/moartesting',
                    'title' =>  'More testing')
              );

function build_tree(&$tree, &$path, $attribs) {
    /* get (and remove) first child from path */
    $elem = array_shift($path);
    if ($elem) {
        if (! array_key_exists($elem, $tree)){
            /*  create a new child if not exist */
            $tree[$elem] = array();
        }
        build_tree($tree[$elem], $path, $attribs);
    } else {
        /* if its a end node, add title and id */
        if ($tree == array()) {
            $tree = $attribs;
        } else {
            $tree = array_merge($tree, $attribs);
        }
    }
}

function render_tree($tree, &$output) {
    if (count($tree)) {         /* more than zero elements */
        $output .= "<ul>";
        foreach($tree as $key => $val) {
            if (substr($key, 0, 2) != '__') {
                $output .= "<li>" . $key . "</li>";
                if (is_array($val)) { /* check for childs */
                    render_tree($tree[$key], $output);
                }
            }
        }
        $output .= "</ul>";
    }
}


$tree = array();
foreach($list as $elem) {
    $path = explode('/', $elem['url']);
    array_shift($path);         /* first element is empty */
    /*  recursively build a tree */
    build_tree($tree, $path, array('__page'  => $elem['page_id'], 
                                   '__title' => $elem['title'], 
                                   '__url'   =>$elem['url']));
}

$output = '';
render_tree($tree, $output);

echo $output;