PHP-GTK is a project that aims to use PHP for real-time applications. I've been playing with it recently and it works great. Unfortunately, it might not quite be what you're looking for, since PHP-GTK is meant for the desktop and won't work in a web environment. But if you're interested, you can read about it here:
http://gtk.php.net/
Otherwise, as Bugermass said, you'll have to resort to Java or Flash. Or, though there isn't much of a user base yet, you may wish to check out Curl: http://www.curl.com/
