Google Authorship is great as it allows you to claim blogs that you publish upon as your own (which helps when people search about you).
Unfortunately Google Authorship is dependent upon 2 critical factors:
A site where you can attach the rel=author code at the end of your Google+ URL link and
A site that Google’s spiders are able to automagically crawl.
Sadly these 2 factors are unavailable for social networks like Twitter, Instagram, App.net, or even Blogger (the latter being out of the loop if you use their dynamic layout within Magazine mode) without inserting an ugly URL in the only place we can (via the link domain spot) which is unacceptable.
Fortunately sites like Vimeo wised up and made themselves Google+ compliant, but the rest of the social networks could probably care less (especially Instagram, Twitter and App.net).
So why not adopt the way of Gravatar (a service by WordPress.com) and login via Oauth to confirm that we own the specific site?
It would make it easier for non-geeks to confirm sites and make it easier for your fans to claim content upon social networks that Google is at war with that Google doesn’t own.