Sme have had their negative PR reversed and gotten confirmation it was about selling links.
From ProBlogger
"I’ve had confirmation now from two sources at Google that this latest round of updates was ALL about the selling of text links. You can see Jeremy Twittered the same thing here. Some of those who have had their updates reversed today were falsely penalized for selling links (like ProBlogger which used to do it but stopped months back)."
More here:
The Google Page Rank Pendulum Swings…. Again