Return number of rows update in query

Hi,
can anybody tell me how to capture the number of rows updated in
an update query inside a stored procedure? This doesn't work but
hopefully you will see what I mean.

CREATE FUNCTION "test" () RETURNS int AS '
DECLARE
v_number_of_rows int;

BEGIN
select into v_number_of_rows
update carbon_user
set email_confirmed = ''Y''
where email_confirmed = ''Y'';
RETURN v_myvar;
END;
' LANGUAGE 'plpgsql';

Thanks in advance!!!

Shane