Word is that Wikipedia has turned on nofollow on links at the direction of Jimbo Wales. In the past Wikipedia voted to remove nofollow from links. There is more discussion of this at slashdot, network world and Google Blogoscoped.
The bottom line? This will do nothing to stop people from spamming pages at Wikipedia. Two years ago (almost to the day), nofollow was announced by Google and friends as a way to stop comment spam. From what I’ve seen, comment spam is still on the rise.
If you want to stop/prevent Wikipedia page spam then only apply techniques that actually work to achieve that goal. Using nofollow does nothing towards accomplishing that goal.