populate array with posts

After getting the posts you can easily put them in another array & then return that array

function get_sponsors()
{
    $args = array(
    'numberposts' => -1,
    'post_type' => 'movies'
    );

    $my_movies = get_posts($args);

    $options = array();
    foreach($my_movies as $m)
        $options[$m->ID] = array(
            'label' => $m->post_title,
            'value' => $m->ID
        );

    return $options;
}