I'm very happy to use WordPress SEO. Good job done and at same time give you good habits and a great lesson.
So, now I see that Google Rich Snippet test tool is liking your plugin yes as it detects the author.
But, WordPress still have some informations missing in hatom type. This include the author of modification and date of this one. Often the item-title is missing (if I remember it's missing in all themes and wordpress nude I try, but woocommerce is adding it for product pages)
Do you plan to add this ? (being in your plugin, for me it's the best place as for SEO it's a one-for-all place and the best I try, including your breadcrumb that I use for replacing the native ones of themes)
I see it's like just 3 lines to add with the good class. Can do it by hack, but if integrate it's better.
Bonus question, is there a difference between rel author and rel publisher ? In case we have a "page" for the website on Google+, must use publisher for this one and author for the personnal G+ account ?