Wikipedia is a great ressource. We all use it. It's become as much a verb as Google has. Do any search, and it's always right up there near the top. For example, I just searched for "George Bush". whitehouse.gov is #1, Wikipedia is #2 (GOP is #3 and bushorchimp.com is #4, but I digress). Why is it so high? Well, everyone and their mother link to it. Search engines work based on link. My writing this has just helped Calgary Grit's search engine results (not by very much, since my page is one small page, but if 1000000 people did, it can make a big difference).
So why am I writing this? Well, in something that most people don't know, you can also tag a link as a "nofollow" link. In that case, you're not saying to the search engines that that counts as a "real" link. To the user, it works the exact same way. To the search engine, it's as if it was never there in the first place.
Now both of those previous paragraphs seem pretty separate, but the reason I write this is that recently, Wikipedia has decided to make all external links nofollow. This means that Wikipedia has effectively stopped allowing their pages to "vote" for others. So on the Wikipedia article about George Bush, the link at the bottom of the page to the official White House biography now no longer counts as a vote from Wikipedia that that is a good article.
So why does this matter? Well, by making all their external links as "nofollow", Wikipedia has effectively secluded themselves from the rest of the internet. They take links from everybody, thus helping out their rankings, but now they no longer share that wealth. I find this to be wrong, since I believe that one of the main purposes for Wikipedia is to freely give out information. By discounting outward links from wikipedia, which are mostly the references for the wikipedia articles, they have made it so that the secondary reference becomes almost more valuable than the first.
Now, there are valid reasons to put the nofollow on, since there are lots of links on wikipedia that shouldn't count towards search engine results, but by putting it everywhere, it could lower the results for lots of truly valid ressources. Hopefully Wikipedia decides to go back on this plan, and maybe implement a system where they can verify a link, so that a good link will actually count, and they can continue to contribute to the overall knowledge of society.