writes "In an attempt to thwart spammers and search-engine optimization mischief, Wikipedia has begun tagging all external links on its site "nofollow", which renders those links invisible to search engines. Whether this is a good thing, a bad thing, or simply unavoidable has become a matter of much debate."
This topic has come up before
and the community voted to remove nofollow back in 2005. This new round of nofollow
comes as a directive from Wikia President, Jimbo Wales.