Sort taxonomy page alphabetically by meta rather than default post date

Question

The user starts at a page showing posts of custom post type, "agent".

Each post displayed shows a region/custom taxonomy it belongs to and links to a page that shows all posts in the region the user clicked.

This is how these posts are currently displayed,

<?php while ( have_posts() ) : the_post(); ?>

Ideally I'd like to to sort these alphabetically by meta_key lname rather than by post date which appears to be the wordpress default.

Thanks for any input

Edit: Script I use to get all custom post type Agents. Puts one specified post as last post.

<?php 
    $loop = new WP_Query( array( 
        'post_type' => 'agents',
        'orderby' => 'meta_value',
        'meta_key' => 'lname',
        'order'=>'ASC',
        'meta_query' => array(array( 'key' => 'lname' )),
        'post__not_in' => array( '93' ),
        'posts_per_page' => -1 ) );
    $loop2 = new WP_Query( array( 
        'post_type' => 'agents',
        'post__in' => array( '93' ) ) );
?>
<?php
    if($loop->have_posts() || $loop2->have_posts()) { 
    if($loop->have_posts()) { while($loop->have_posts()) { $loop->the_post();
?>

Answer 1

Maybe try something like this before the loop:

<?php
query_posts( wp_parse_args( $query_string, array(
    'meta_key' => 'your_meta_key',
    'orderby' => 'meta_value'
    ) ) );
?>

Answer 2

Pretty much the same as the above to answers, but using meta_query instead of meta_key. meta_key was deprecated as of WP 3.1. I'm not sure if ordering by meta_value still works in this case, however.

$wpse20766args = array(
     'orderby'  => 'meta_value',
     'order'    => 'ASC',
     'post_type'    => 'agent',
     'posts_per_page' => -1,
     'meta_query'   => array(
        array( 
            'key' => 'lname'
        )
     ) 
);

$wpse20766q = new WP_Query( $wpse20766args );

// then the loop...
if( $wpse20766q->have_posts() ):
while( $wpse20766q->have_posts() ) :
$wpse20766q->the_post(); 

// do stuff...

endwhile;
endif;

Answer 3

This is what ended up working.

global $wp_query;   

query_posts(array_merge(array('orderby' => 'meta_value', 'meta_key' => 'rw_lname' ),$wp_query->query));

<?php while ( have_posts() ) : the_post(); ?>