Although authorship markup is specific to Google, and specifically Google+, rel=’author’ is the latest trust signal now that links have been spammed to the point of being passe. Semantic markup, aka structured data, is helping to add meaning to HTML code, and Google is using it to highlight data in search results.
It’s not a bad carrot for being an early adopter of this technology. Google’s vision of the Internet does not always line up with the way that people actually do business, but Authorship is something that makes a lot of sense. It makes more sense to trust an author than it does a link from a domain or a server ‘neighborhood’, but there are plenty of real-world examples of how articles don’t quite conform to such simple rules.
Google put an Authorship FAQ on Webmaster Blog yesterday to clear up some of these issue with implementation such as: multiple languages blogs, co-authors, using rel=’publisher’ for your Google+ Page, and what Authorship shouldn’t be applied because it would be, “less perspective/analysis oriented.” Don’t forget to check the forums for more Google Authorship Tips.