Rich Snippets, a type of Structured data, will really define SEO in 2013. The impact of Rich Snippets can already be seen in Google Search Engine results when you look up particular people, recipes, events, companies in a specific industry and other areas using specialized markup on websites.
Authorship will allow you to take credit and link up with content you have written. Another enhancement from using authorship markup is that your picture from your Google+ profile will show up in Search results, giving your posts extra visibility.
Here is an introduction and discussion on working with Structured data such as Rich Snippets and Authorship with Dan Petrovic of DejanSEO and friends in a recent Google Hangout.