If you sudo to a non-root user, you get a permission denied error.
Here's an example:

    $ ansible myserver.example.com -m postgresql_db -a "db=mydatabase" -u ubuntu -s -U postgres
    myserver.example.com | FAILED >> {
        "failed": true,
        "msg": "chmod: changing permissions of `/tmp/ansible-
        1351092257.96-157699143369671/postgresql_db': Operation not
        permitted\n/usr/bin/python: can't open file '/tmp/ansible-
        1351092257.96-157699143369671/postgresql_db': [Errno 13]
        Permission denied\n",
        "parsed": false
    }

The problem is that ansible is doing the chmod as the sudo user
when it should be doing it as the remote user.