$ua = strtolower($_SERVER['HTTP_USER_AGENT']);

$uachar = "/(nokia|sony|ericsson|mot|samsung|sgh|lg|philips|panasonic|alcatel|lenovo|cldc|midp|mobile)/i";

if(($ua == '' || preg_match($uachar, $ua))&& !strpos(strtolower($_SERVER['REQUEST_URI']),'wap'))
{
    $Loaction = 'mobile/';

    if (!empty($Loaction))
    {
        ecs_header("Location: $Loaction\n");

        exit;
    }

}

来源: 腾讯:http;//www.qq.com和http://blog.sina.com.cn/s/blog_54318f230100u30w.html