Planet13 - 6:36 pm on Oct 10, 2013 (gmt 0)
But look at the way Wikipedia, Facebook, Twitter, blogs, forums etc. are utilising the nofollow. To me it appears that the vast majority of nofollows are used in a way contradicting the G Guidelines.
I think that the reason those particular sites use nofollow is because they realize that people will spam the daylights out of them if they allowed links to pass page rank.
So it isn't so much of an editorial statement that wikipedia thinks that the sites they link out to suck. It is more just a precaution to avoid people posting (even more) spam on those sites.