function twentyten_custom_excerpt_more($output)
{
    if (has_excerpt() && !is_attachment()) {
        $output .= twentyten_continue_reading_link();
    }
    return $output;
}

/**
 * Adds a pretty "Continue Reading" link to custom post excerpts.
 *
 * To override this link in a child theme, remove the filter and add your own
 * function tied to the get_the_excerpt filter hook.
 *
 * @since Twenty Ten 1.0
 * @return string Excerpt with a pretty "Continue Reading" link
 */
function twentyten_custom_excerpt_more($output)
{
    global $post;
    if (has_excerpt() && !is_attachment()) {
        // don't show continue link for nh_message types
        if (post_type_exists('nh_message') && $post->post_type == 'nh_message') {
            return $output;
        }
        // add continue link for all others
        $output .= twentyten_continue_reading_link();
    }
    return $output;
}

/**
 * Replaces "[...]" (appended to automatically generated excerpts) with an ellipsis and twentyten_continue_reading_link().
 *
 * To override this in a child theme, remove the filter and add your own
 * function tied to the excerpt_more filter hook.
 *
 * @since Twenty Ten 1.0
 * @return string An ellipsis
 */
function twentyten_auto_excerpt_more($more)
{
    return ' …' . twentyten_continue_reading_link();
}