First activate the `image_album_statistics` plugin.
Then I use this:
`<?php printLatestImages($number=1, $albumfolder='', $showtitle=false, $showdate=false, $showdesc=false, $desclength=40,$showstatistic='',$width=600,$height=600,$crop=false);?>`
It gives me the latest image in the entire gallery at 600px wide or 600px high (depending on the orientation of the image)
The way I am showing it is not the right way but it works and probably makes more sense to you.
You should also read:
http://www.zenphoto.org/documentation/plugins/_plugins---image_album_statistics.php.html
and
http://www.zenphoto.org/2008/04/how-to-read-the-zenphoto-functions-guide/