Back in October, Google's John Mueller told us directly and clearly that authorship is not used for rankings. That has not changed, as John Mueller said it again in a Google Webmaster Help thread yesterday.
Authorship only plays a role with the "in-depth-articles" feature, and otherwise has no effect on ranking in web-search at all.
Yes, in March, Matt Cutts told us that authorship is used for in depth articles but outside of that, Google is not using it.
I should add a caveat that Google has been hinting at working on a good guy algorithm that may use authorship and forms of author or content specific authority to promote web pages. There is a good chance that authorship in this form or future forms, may play a role in rankings. Another point is that authorship may improve your click through rate because of the extra image in the search results.
But for now, authorship, outside of the very edge case of in-depth-articles, has no role in rankings.
Forum discussion at Google Webmaster Help.