Also, I have found that the problem when using a 'fieldmap' array is that if you define an array, the mappings must not include '_field". That format works for individual mappings, but not for a fieldmap array. So while the sample above works, this code here gives the same result. The comments inside rcube_ldap.php seem to indicate that the format I included above is deprecated, so this format is probably the preferred method.
$rcmail_config['ldap_public']['LESD'] = array(
'name' => 'Lane ESD',
'hosts' => array('xxxx.lesd.k12.or.us'),
'port' => 389,
'use_tls' => false,
'user_specific' => false,
'base_dn' => 'ou=People,dc=lesd,dc=k12,dc=or,dc=us',
'ldap_version' => 3,
'search_fields' => array('mail', 'gn', 'sn'),
'fieldmap' => array(
'name' => 'cn',
'email' => 'mail',
'surname' => 'sn',
'firstname' => 'gn',
'phone:work' => 'telephonenumber',
),
'sort' => 'sn',
'scope' => 'list',
'filter' => '',
'fuzzy_search' => true
);