Update timestamp on update

I have a table like:

CREATE TABLE products (
id int,
status int,
last_status_change timestamp DEFAULT now()
);

What I would like is that whenever the status is changed the
last_status_change timestamp is updated to the current time. I have had
a look at the rules and what I want would be similar to:

CREATE RULE last_status_change AS ON UPDATE
TO products WHERE NEW.status <> OLD.status
DO UPDATE products SET last_status_change = now() WHERE id = OLD.id;

Except of course that the above is recursive and doesn't work.

How can I do this?

Jeff