I was a bit shocked to see that Wikipedia removed the nofollow link attributes from its pages. A thread at WebmasterWorld named Too many Wikipedia links?, which was primarily concerned with being penalized by Google for having too many links from the Wikipedia. But, as did some others in the thread, I thought Wikipedia used the nofollow attribute for links. It looks like they have removed them from all the links on the pages.
Take a look at the Yahoo! Wikipedia and then view the source and do a find on "nofollow". Nothing to be found.
So that does bring the question. Does one have to worry about having too many links from the Wikipedia?