Oh, an idea involving [man]array_filter/man comes to mind:
<?php
$array = array(1, 2, 3, NULL, 4, 5, NULL, 6, 7, 8);
print_r($array);
echo "<br />\n";
$array = array_filter($array, create_function('$value', 'return $value !== NULL;'));
print_r($array);
?>
EDIT:
I really should not have blank values in this field. I'd just have to go into my db and fix it.
Yes, that would be even better.