Hoople - 2:27 pm on Dec 21, 2011 (gmt 0)
Not knowing the url makes this more of a guess.
If the url has no date aspect within it I would update the 2008 article and leave it at the old url. Post a copy of the old article at a new url with a link back to the updated article.
If the url does have a date aspect within it I would 301 redirect that url to the updated version of the article at a new url.