PHP menu generator

This is the code that generates the menu you can see over on the left.

Update: Edd, who uses a slightly modified version of this site, wanted an external link in his nav menu. This required a slight mod to the code, since external pages can't be checked for last-modified times. I also took the opportunity to mark them with their own icon.

<?php

    // The menu bar is built from the array below.  Since the HTML generation
    // code is recursive, depth is unlimited.  Syntax should be fairly obvious
    // from the current array.
    //
    // TODO: either get the heading from the page or set it there -- having it
    // in two different places doesn't make sense, although an override might.
    $pageArray = array(
        "Home" => "/index.php",
        "Bio of a random hacker" => "/bio.php",
        "Contact details" => "/contact.php",
        "Licensing" => "/licensing.php",
        "Webcomics" => "/comics.php",
        "Other people" => "/people.php",
        "Code" => array(
            "Python random name generator" => "/code/cfnamegencode.php",
            "PHP syntax highlighter" => "/code/syntaxhlcode.php",
            "PHP menu generator" => "/code/phpmenucode.php",
            "xmms sleep script" => "/code/xmmssleepcode.php",
            "irssi channel beeping script" => "/code/irssichanbeep.php",
            "Python logfile reader class" => "/code/logfile.php",
            "Home directory analysis script" => "/code/homediranalysis.php",
            "Remote execution script" => "/code/remoteexec.php",
            "Dialup control panel" => "/code/dialupcp.php",
            "Hamming number calculator" => "/code/hammingnums.php",
            "PHP python datatype parser" => "/code/pythontypes.php",
            "Python TOC generator" => "/code/maketoc.php",
        ),
        "Shiny stuff" => array(
            "Campus proxy squid hack" => "/shiny/proxyserver.php",
            "Phone stuff" => "/shiny/phone.php",
        ),
        "Writings" => array(
            "How to send an electronic notice" => "/writings/notice-netiquette.php",
            "How to survive Computer Methods pracs" => "/writings/howtosurvivecm.php",
            "How not to cheat" => "/writings/hownottocheat.php",
            "Linux for computer scientists" => "/writings/linuxforcompsci.php",
            "Teach yourself programming" => "/writings/learnprogramming.php",
        ),
    );

    function iecho($indent, $text) {
        // Indents the HTML for the menu -- purely making the code look
        // pretty, no effect on rendering.
        for ($i=0; $i<$indent; $i++) {
            echo "\t";
        }
        echo $text;
    }

    function isNew($url) {
        $url = "base" . $url;
        if (filemtime($url)) {
            if (time() - filemtime($url) < 604800) { // 604800 secs in a week
                return true;
            }
        }
        return false;
    }

    function isAbsolute($url) {
        if (strpos($url, "://") != false) {
            return true;
        } else {
            return false;
        }
    }

    function navGen($pageArray) {
        // Takes the array given in $pageArray and generates the navigation
        // bar from it.
        //
        // TODO: Finish the version that handles authentication, etc. and put
        // that here.
        static $indent = 1;

        $currentFile = get_included_files();
        $currentFile = basename($currentFile[0]);

        iecho($indent, "<ul>\n");
        $indent += 1;
        foreach ($pageArray as $name => $url) {
            if (is_array($url)) {
                iecho($indent, "<li>$name\n");
                navGen($url);
                iecho($indent, "</li>\n");
            } else {
                // Is this the current page?
                if ($url == $currentFile) {
                    $class = " class=\"navcurrent\"";
                } else {
                    $class = "";
                }
                // Is this page external?
                if (isAbsolute($url)) {
                    // If so, mark it as such.
                    $icon = "<img src=\"common/external.png\" alt=\"external\" />";
                } else {
                    // If it's local, we can check for newness.
                    if (isNew($url)) {
                        $icon = "<img src=\"common/new.png\" alt=\"new\" />";
                    } else {
                        $icon = "";
                    }
                }
                iecho($indent, "<li>".$icon.
                                "<a$class href=\"$url\">$name</a></li>\n");
            }
        }
        $indent -= 1;
        iecho($indent, "</ul>\n");
    }

?>
<div id="navbar">
<h1>jerith.za.net</h1>
<?php navGen($pageArray); ?>
</div>