Spam is destroying the internet yet again...
Wikipedia is probably one of the most tempting places to put Spam - you can edit it however and whenever you like. There are few controls in place to stop abuse.
It'll be interesting to see what Google do from this - I would expect that a large amount of certain websites receive much of their ranking due to links originating from Wikipedia. If Wikipedia sets it so that Google ignores the links, then they might disappear.
We'll see what happens, but should be good to see if Google begins to work on ways to exclude random spam links while including genuine links to relevant articles.