How to Use Registration States

I don't have an answer for how multiple registration states could be "default", but as to the "Show on form" option, checking that box causes the registration status option to show up on the registration form-- i.e. the form people fill out when registering. This form usually appears at a path like node/[node:nid]/register, with [node:nid] being the NID of the node that people are registering for.

One issue I noticed, however, is that there don't appear to be permissions for the various registration states. If, for example, I only want site admins to be able to set the status, I can't do that; the "State" field appears even for anonymous or other non-admin users.

An alternate method, which may help with the permissions issue and with granularity, would be to accomplish "registration statuses" via a field on the registration entity, or via Taxonomy. That way, multiple configurable registration statuses could be created, per-entity-bundle, and of course permissions could be accomplished via the Field Permissions module.

Hope this helps!

A permission to make to registration state only available to certain user roles does seem to make sense. I will add it with a form_alter() for now.

<?php
/**
 * Implements hook_form_alter().
 */
function modulename_form_alter(&$form, &$form_state, $form_id){
  if ($form_id == 'registration_form') {
    // Add permission for state field
    $form['state']['#access'] = user_access('modulename registration state');
  }
}

/**
* Implementation of hook_permission().
*/
function modulename_permission() {
  // Add custom permission for editing a registration state of a user
  return array(
    'modulename registration state' => array('title' => t('Change states of a registration')),
  );
}
?>

I believe this is a very important enhancement. Currently the registration form displays all states (marked to display in form), which practically makes a Pending state useless because a user can just change to the desired state when registering.

When the state is marked as not in form, there is no way to change the registration state, because it won't be in ANY form.

This is already implemented.

  $form['state'] = array(
    '#type' => 'select',
    '#title' => t('State'),
    '#description' => t('State of this registration'),
    '#default_value' => ($state ? $state->identifier() : $default_state->identifier()),
    '#options' => $states,
    '#access' => !empty($states) && user_access('edit ' . $registration->type . ' registration state')
  );

This is already implemented.

  $form['state'] = array(
    '#type' => 'select',
    '#title' => t('State'),
    '#description' => t('State of this registration'),
    '#default_value' => ($state ? $state->identifier() : $default_state->identifier()),
    '#options' => $states,
    '#access' => !empty($states) && user_access('edit ' . $registration->type . ' registration state')
  );

Indeed. I accidentally overwrote my -dev version of the module with the 1.0 version (thanks drush)