I can't find the reference, but I remember reading here on HN that someone investigating a large drop in traffic to pages with #1 organic rankings traced it back to the profile photo that got added to pages with authorship attribution. There didn't seem to be a traffic drop on pages with #2 or #3 etc., so the author came to the conclusion that the profile thumbnail was causing their listing to be mistaken for an ad.
Anyone remember that article?
The short version is that the site was affected by Google's Penguin webspam algorithm. It had nothing whatsoever to do with authorship.
Here is the article you are referencing: http://www.jitbit.com/news/183-how-google-authorship-decreas...