Rails 2.3 nested forms and transactions

Hi all,

Does anyone know if the new nested object forms in Rails 2.3 supports transactions on save? (http://guides.rubyonrails.org/ 2_3_release_notes.html#nested-object-forms)

Supposing you had a form that let users of an app create an account and the admin user account in the same screen, nested object forms seem like a good fit. However, creating the customer account and the user need to be done as a transaction (you wouldn't want a customer without an admin user or vice versa).

How is this handled? Is this the default? Does it need to be implemented in a :reject_if proc?

Thanks!