I wrote a great Wikipedia article about my company's product with 1 extermal link to my site. The wiki article does not rank very high. But I spent a lot of time on it. Anyway, one of my competitors is now, on a daily basis, completely editing the wikipedia article and is basically turning it into an ad for their company's product. They put around 20 links to their web site in the article and deleted my link and all the good info. Does wikipedia links or articles have any affect on your site's SEO?
Please don't spam Wikipedia! Links from wikipedia are nofollow. That won't be beneficial for your SEO.
Links from wikipedia, although nofollow will help your SEO. But, don't spam there and if you see others spam you can report those, tell other editors and their links and content will get removed.
If you are really doing contribution to Wikipedia in niches that are related to your website and leave your link as a source there is nothing bad about it. Of course if you change others contribution just to get links, then you have to stop doing it!
wikipedia links are authority links are definitely useful when it comes to seo.. you can alwyas edit your articles and remove their links or report is as spam..
I'm sure wikipedia has some things to do with SEO... it's an authority site. It may have a nofollow tag but still, as a search engine sees an authority site linking to yours - that might help!