Here is a quote directly from Google’s Inside Search blog:
We now support markup that enables websites to publicly link within their site from content to author pages. For example, if an author at The New York Times has written dozens of articles, using this markup, the webmaster can connect these articles with a New York Times author page. An author page describes and identifies the author, and can include things like the author’s bio, photo, articles and other links.
If you run a website with authored content, you’ll want to learn about authorship markup in our help center. The markup uses existing standards such as HTML5 (rel=”author”) and XFN (rel=”me”) to enable search engines and other web services to identify works by the same author across the web. If you’re already doing structured data markup using microdata from schema.org, we’ll interpret that authorship information as well.
We know that great content comes from great authors, and we’re looking closely at ways this markup could help us highlight authors and rank search results.
In simple terms, this means that you should make sure that all your content – no matter where it is published – identifies you as an author. This will help link all your content together, create your author profile, and use that as yet another criteria in ranking and searching. Those of you publishing with WordPress shouldn’t worry at all – adding authorship is either already done or will take a minor modification to the theme. WordPress provided both author pages and XFN markup out of the box for years.