We've been hit by the penguin update. We've pretty much gone down to 0 traffic on one of our domains that has 7 websites spanning off it. The way this website (newspaper website) works is multiple news sites running off the root domain in subfolders [e.g. www.newswebsite.com/site1/] The sites have never really had much traffic and not much off-page SEO has been done. The only recent changes I made was to introduce social media in the forms of Facebook & Twitter. Interestingly, one of our newspapers runs off it's own domain, exactly the same layout but traffic has doubled. Does this indicate that having the news websites in subfolders has affected the way it is displayed in search? If so, what can I do? Would having them on subdomains make any difference?
Although the site itself is there, nothing comes up at the link you posted. "Not much off-page SEO has been done." How much is not much? If this is not caused by bad links, then it's not Penguin! There can be all kinds of other reasons.