Wikipedia doesn't want to become the playground of spammers so they implemented a major change today that makes their website less interesting to spammers.
Any URL on Wikipedia website that points to a location other than en.wikipedia.org is now stuffed with rel=nofollow tag meaning Wikipedia won't help bring any Google juice for your site.
So whether it's the CNN website or a PayPal phishing site or an illegal Viagra store, Wikipedia will have the same policy for all - we don't trust you so you get the rel=nofollow tag..
Now that's a worrying development. The search engines would believe that Wikipedia is the actual owner of the content and will rank their pages higher in organic listings even when the content was sourced from other "credible" sites like CNN, Engadget or even your mom's blog.
Let's illustrate with an example:
Say you discover a cool feature in the iPod (called Stylus) and blog about it. Tomorrow, the Wikipedia contributors append the details of iPod Stylus (your discovery) to the Wikipedia page on iPod. They do attribute your blog but search engines will never see that attribution (or read your blog via Wikipedia) because of the rel=nofollow tag.
Now that Wikipedia enjoys higher credibility and trust (read PageRank), the search algorithms will rank the Wikipedia iPod page higher than yours (for queries like iPod Stylus) because the search engine bots are not aware that Wikipedia's content is actually based on your blog page.
Result, your site appears after Wikipedia in the "iPod Stylus" search results and you get less or no traffic while Wikipedia gets to enjoy all the fruits of your labor..
Penalizing everyone for the spammy actions of few individuals is just not right. They should rollback this change immediately.
Related: How to Track Wikipedia Articles like Google Alerts