Yes you are right that Google declared at 21 Sep 2009 that they do not consider meta-keyword in search ranking anymore.
But that doesn't mean that others search engine also ignoring this one aspect. Bing, Yahoo, Yandex and similar other popular search engines still consider meta-keywords in search ranking.
So it's up to you, that what strategy you are adopting. Hence, meta-keyword are not harmful for your website.