Not to mention the amazing amount of sites that scrape Wikipedia content, some of which actually provide "dofollow" links to your site.
As is said earlier, wikipedia helps you to drive traffic to the website and as well in SEO. I believe so, because i checked my backlinks from GWT. It showed me wikipedia links. If Google doesnot follow links from wikipedia, then it should not be shown as external links for the website. We know google never shows all the backlinks for a web page for a query link:www.example.com. Google shows wikipedia links mostly in its SERPs & give more weightage to the site. So any links from wikipedia will definately will have little weightage in SEO.
What you're seeing is Google acknowledging the link is there, but it's not following it. It's like walking past a house with a "No Trespassing" sign on the fence. You know it's there, but you respect the sign and stay out of the yard.
Here's my experience with Wikipedia... 1. Foolishly, not knowing any better, I posted links on an entry about me (probably originally posted by one of my publishers). Links were to my official site and a couple of originally MFA sites that I later (in 2006?) tried into ebook sites (see sigs). 2. Much personal embarassment followed as I was verbally beat up because I'd unknowingly (through pure and simple ignorance) violated the "no autobiographical material" rule. Finally, though, a senior moderator cleaned up article, told whiners to chill, and article on me (with three links to sites shown below) "stabilized." 3. As far as traffic, and here I embarass myself again unfortunately, I don't think I get much traffic from my current three links author page... 4. But in 2005(?) I did stick links up on the limited liability company page (links pointed to my llcsexplained.com site). Traffic spiked... but no kit sales occurred. I.e., sure, I got a couple hundred additional people a day visiting the site... but saw no bump in sales of my downloadable do-it-yourself incorporation ebooks. (I concluded wikipedia visitors aren't buyers... they're researchers.) 5. Tangential remark... I actually used to teach llc and s corporation tax law... and I went to quite a bit of editorial work to clean up and correct the nonsense that inexpert "editors" and "writers" created about llc formation, taxation, s corporations, etc. I figured (again very naively) that if I corrected a bunch of errors, added content, etc., that it'd be fair if i put in a link to my significantly richer in on-topic resources site... that position was (brutally) rejected by wiki editors (who probably included MFA site owners and competitors). Very embarassing. Again. (But for me, another conclusion: Wikipedia editing is a waste of time... you get nothing for your effort except grief... and any quality you inject can be quickly corrupted.) 6. I assume (just based on logic) that because the Wikipedia links are pretty high quality (as least if they're old) that search engines weight them heavily... This would be what I'd do if someone made me king of Google for a day... 7. Obviously, obviously, obviously, some people have having PR agencies write up their wikipedia entries. I guess technically that's not "autobiographical" but it's certainly a violation of the spirit of the enterprise if not the letter of the law. See for example Tim O'Reilly's entry. (Him of O'Reilly & Associates, publisher of books many of you read and use.) Sorry for going on so long...
What doesn't make sense to me about that--and I don't mean to disagree with you but perhaps with Google's honoring the nofollow tag--is that Wikipedia links are such a good "signal" of page's worthiness. Wikipedia, as I understand it, instituted the nofollow tag policy to deal with spammers (er, I guess, technically including me) posting links. But the links are great ways to find or spot authoritative sites. Just saying...
Wikipedia is simply a high visibility authority site. It has top rankings because it has so many backlinks and hundreds of thousands of inner links, which is why it's on top for so many keywords. It gets oodles of hits, and its inner pages get oodles of hits. If your link is on there, you're exposed to that huge benefit.