Are you in wikipedia's spam blacklist?

Do you have your site in wikipedia's blacklist then I recommend get it removed immediately. Personally we don't know any of our sites or client sites in wikipedia blacklist.

meta.wikimedia.org/wiki/Spam_blacklist

Wikipedia has a strong relationship with Search engines, Wikipedia does share this information to Search engines and it will result in your site loosing credibility with search engines.

Mattcutts of Google denies any automated penalty

"If you do a search for [wikipedia spam blacklist], the first result is helpful. It gives pointers to various strings and urls that Wikipedia has blacklisted on their site.

I'd characterize that list as much like a spam report: the data can be useful, but at least in Google it wouldn’t automatically result in a penalty (for the reason that site A might be trying to hurt site B).

That could be one of the things jehochman was referring to."

http://www.searchenginejournal.com/wikipedia-spam-resulting-in-google-yahoo-penalties/5854/