Matt cutts tweeted that he has made an update targeting "spammy" aka money making keywords.
This is why some of you might have seen some shuffling around the serp today or/yesterday.
Here is the link for the tweet : https://twitter.com/mattcutts/status/344574964365672448
There are absolutely no evidence like some might have claimed that this update was targeting sape links even if you were hit and you were using them, it might be only due to the fact that you are targetting this kind of keywords.
Good luck !