This progess meter is based on the yahoo user interface library and alternative php cache (APC). You will need both of these for it to display properly. PHP 5.2.0 or higher is also required. (I have written a previous article on alternative PHP cache here).

He gives a brief overview of how things work (including the php.ini setting to make it happen) and has a screenshot of the resulting output. You can check out the demo here or just grab the source and jump right in.