INSERT... RETURNING with a function

I've written a straightforward insert function, but using the
RETURNING keyword for the first time. If I try running the test case
I get the error:

ERROR:  query has no destination for result data
CONTEXT:  PL/pgSQL function "nonauth_users_insert_new_udf" line 7 at
SQL statement

I'm not sure what I need to do to catch the return value as I've
tried a few different combinations and nothing has worked for me so
far. The Insert statement as it is below but outside of a function
works and returns the id. Any input is much appreciated.

I'm running version 8.4

Regards,
Iain


/*test*/
/*
select nonauth_users_insert_new_udf(
'testuser1', 'testuser1@example.com', 'xDvTfTOB99mG6zSyMjYtVhUd3P4',
'4DhFLU1YJU5Oz/+XGqh3npn2RJQ'
);
*/

CREATE OR REPLACE FUNCTION nonauth_users_insert_new_udf(
    _username varchar
  , _emailaddress varchar
  , _salt char
  , _hash char
  ) RETURNS int
AS $$
  BEGIN

   Insert into nonauth_users ( username, emailaddress, salt, hash,
added )
   values ( _username, _emailaddress, _salt, _hash, now() )
   RETURNING nonauth_users_id;

   --the query works this way though
  --RETURN currval(pg_get_serial_sequence('nonauth_users',
'nonauth_users_id'));

  END;

$$
LANGUAGE plpgsql;