John Resig's prettyDate - timezones

/*
 * JavaScript Pretty Date
 * Copyright (c) 2011 John Resig (ejohn.org)
 * Modified to compensate for timezones by fuxter (fuxterz@gmail.com) 2012
 * Licensed under the MIT and GPL licenses.
 */

// Takes an ISO time and returns a string representing how
// long ago the date represents.
function prettyDate(time){
    var date = new Date((time || "").replace(/-/g,"/").replace(/[TZ]/g," ")),
        date = new Date((date.getTime() / 1000 - date.getTimezoneOffset() * 60) * 1000),
        diff = (((new Date()).getTime() - date.getTime()) / 1000),
        day_diff = Math.floor(diff / 86400);

    if ( isNaN(day_diff) || day_diff < 0 )
        return;

    return day_diff == 0 && (
        diff < 60 && "just now" ||
        diff < 120 && "1 minute ago" ||
        diff < 3600 && Math.floor( diff / 60 ) + " minutes ago" ||
        diff < 7200 && "1 hour ago" ||
        diff < 86400 && Math.floor( diff / 3600 ) + " hours ago") ||
        day_diff == 1 && "Yesterday" ||
        day_diff < 7 && day_diff + " days ago" ||
        day_diff < 31 && Math.ceil( day_diff / 7 ) + " weeks ago" ||
        day_diff > 31 && "ages ago";
}