Magento : Enable Address Fields on Customer Registration Forms

In order to enable address fields in Magento customer registration forms you only need to enable the attribute setShowAddressField.

To do so either add the following in your template or in the base local.xml (/app/design/frontend/base/default/layout/local.xml):

<customer_account_create> 
  <reference name="customer_form_register"> 
    <action method="setShowAddressFields">
      <param>true</param>
    </action> 
  </reference>
</customer_account_create>

As always, make sure to reload your cache afterwards. This setting will enable to execution of

<?php if($this->getShowAddressFields()): ?>

in register.phtml (/app/design/frontend/base/default/template/customer/form/register.phtml).

Done! :)