What has recently changed is 

[2012-10-16: The number of reviews required to accept/reject suggested edits has been increased to two Network wide (versus 1 before) and three on Stack Overflow. (versus 2 before)
Moderators can still cast final vote like before][1]

As I understand it, in particular the edit reviews on SO were appalling with even blatant spam getting through so the problem has been 'fixed' network wide. 

  [1]: https://meta.stackexchange.com/questions/59445/recent-feature-changes-to-stack-exchange