Very similar to the MySQL modules Mark Theunissen has provided earlier, we now have some PostgreSQL modules from Lorin Hochstein.
https://github.com/ansible/ansible/blob/devel/library/postgresql_db
https://github.com/ansible/ansible/blob/devel/library/postgresql_user
As you can see, these take basically the same kinds of arguments.
These are new, so as usual, testing and comments are great to have.
If you want to create users and databases via Ansible, either the PostgreSQL or MySQL modules may be very interesting to you.
Check em out!
--Michael