I started to develop an EXIF module for Drupal 6. This module would come woth Image module.
From now, my module only displays a "Show EXIF" button on each image node, and clicking on this button makes an AJAX call to display EXIF data (at the moment, it is only a raw array data).
I am planning to add a configuration page, where administrator can choose which EXIF data to display.
Reading IPTC data can eventually be done.
I use PHP's EXIF extension, so you only need to activate it in php.ini (no need for PEL).
To EXIF maintainer: please tell me if you are working on a Drupal 6 port, and if my work interests you.
You can get an alpha version of my work in attachment.
Any thoughts or questions are welcome. :)