take a look at this Matt's page: http://ma.tt/2008/12/sydney-zoo-opera-house/mcm_5817/
The big image on the top is linking to the next image in the gallery, not to the full-resolution file version.
My image.php has this code to link to the image itself:
<div class="attachment-image"> <a href="<?php echo wp_get_attachment_url($post->ID); ?>"> <?php echo wp_get_attachment_image($post->ID, 'full'); ?> </a> </div>
How can I modify this to link the main image to the next image in gallery?