Geez... much easier to put this in classes.php, like I was saying. You [i]don't need to touch the SQL code,[/i] zenphoto is programmed right, and the database model is [i]good[/i], trust me. What you wrote above won't even work, so don't continue going that direction...
To select/insert based on your "key" you just need to modify [b][i]one line[/i][/b] to the album class:
Find:
`$new = parent:

ersistentObject('albums', array('folder' => $this->name));`
Change to:
`$new = parent:

ersistentObject('albums', array('folder' => $this->name, 'year' => '2006'));`
You're modifying the set of unique keys used to find records in the database. Just add an item to the array defining a new unique key. Note that all the albums you want to select/modify have to have the year as 2006. If you want to pull 'year' from the user and put it in there, it's easy too, just use a $_GET['year'] variable and pass it through the query string...
Look, zenphoto is clean, don't mess it up with SQL hacks, use the elegant (admittedly undocumented) structure already in place ;-)