This is my latest article on , (http://searchengineland.com/chasing-authorrank-waste-time-185140) in which I speculate that SEOs who spend their time talking about AuthorRank would be better off spending their mental energy elsewhere.
The first thing to note is that Google does not talk about AuthorRank, they only talk about Authorship, which is tied to their rel=author markup and Google Plus. AuthorRank is a term made up by people outside of Google.
However, Google itself has fanned the flames with statements such as the one I show here from Eric Schmidt which is extracted from his book, The New Digital Age.
In summary, my opinion is that it is not here yet, and that we should focus our energies in building real world authority, not because of AuthorRank, but because it is simply the best strategy for our businesses.