A study by Conductor shows only 9% of technology blogs have fully implemented the authorship, rel=author, attribute fully on their site. That is less than 1 out of every 10 blogs.
This is somewhat shocking because (1) these are technology blogs that should know about the feature and (2) it is shown to increase the click through rate from the Google search results to the web site. A higher click through rate leads to more ad impressions, which leads to more revenue for these technology blogs.
We’ve seen reports of authorship increasing click through rate by 30% to 150% or more.