I've made the following changes to my copy of the Registration module [unreleased] which Sam may want to add..

In RegisterPage_Controller class add
   
   function init() {
      parent::init();
      
      if(!$usersGroup = DataObject::get_one("Group", "Code = 'users'")) {
         $group = new Group();
         $group->Code = 'users';
         $group->Title = "Users";
         $group->write();
      }
   }

Replace Form() method with :
/**
    * Return the edit form for the current user
    */
   function Form() {
      // Get the fields from a new member - seems like a good default
      $member = new Member();
      $fields = $member->getMemberFormFields();
      $fields->replaceField('Password', new PasswordField('Password') );
      $actions = new FieldSet(
         new FormAction('register', 'Register')
      );

      $form = new Form(
         $this,
         'Form',
         $fields,
         $actions,
         new RequiredFields("FirstName", "Surname", "Email", "Password")
      );

      return $form;
   }

this then gives a password field rather than a text field, and adds a validator

Replace register() method with :
   /**
    * Save the profile details
    */
   function register($data, $form) {
      // Create a new member and save the form into it
      $member = new Member();
      $form->saveInto($member);
      
      // Write to the databsae
      $member->write();
      
      $groupMember = new Group();
      $groupMember->addToGroupByName($member, 'users');
      
      // To do: add a status message on the form, using the standard form message system

      // Return to the original form
      Director::redirect($this->Link() . 'thanks');
   }

This adds the new Member to the Group we created in init() -- 'users'

chrisdarl - if you want to suggest code changes to the modules please use open.silverstripe.com and submit the change as a patch / diff file so we can merge it into the module otherwise it just sits round on the forum for years.

When you make your ticket on open.silverstripe.com please ensure you list the changes you made and why and tag it with the correct component / tags.