I have implemented a quick hack for the search feature. It needs to be integrated into the whole zenphoto framework (which I am not very familiar with). Files are at http://rv101.dyndns.org/~rv101/zen
[search.php] goes to your zen root document.
This is a copy of themes/default/index.php with a search form, and it uses next_search_album() instead of next_album(). In this files, the function next_search_album() may be integrated into the file zen/template-functions.php.
[classes.php] needs merging with zen/classes.php
This adds the method searchAlbums() to the Gallery class. It is a copy of the method getAlbums(), but does a SQL query instead of scanning a directory for albums. This code needs to be secured (nasty things can be done here).
[TODO]
1-SQL query code needs to be secured
2-Code needs to be integrated with the zenphoto framework (add maybe a new context, put search.php in themes)
3-Add the navigation index on the bottom of the search results
Hope this may be useful to someone
demo is available at http://gallery.rv101.dyndns.org