Auto approve an user after registration (Services)
Jose - Make sure you have "Require e-mail verification when a visitor creates an account" unchecked in your Drupal admin under /admin/config/people/accounts

Also, there seems to be a bug in the services module that doesn't set the password correctly if you send it through the REST service. If you apply this patch, you should be able to set the password and the user should be able to log in right away.

https://drupal.org/files/issues/user_create-2198005-1.patch