Spinning the treatment of ecommerce product descriptions off from some questions regarding authorship that have arisen in our current discussion... Google Authorship not (yet) a ranking factor, per John Mueller http://www.webmasterworld.com/google/4613727.htm
There are still a lot of sites left out of Authorship (yo, ecommerce anyone? or just business or organization sites?) for it to be any kind of ranking factor.
There's no reason why authorship couldn't be a ranking factor for searches where authorship is relevant, and not for searches where it isn't.
In the John Mueller video Hangout that inspired the above, there are several inescapable suggestions that... at least with regard to product descriptions
... authorship will not be relevant.
As I read it, Google is more or less officially bypassing the issue of who originated product descriptions, and will be looking to factors of site authority, query intent, and to other content on the ecommerce site to determine rankings... Webmaster Central 2013-09-27 John Mueller https://plus.google.com/events/cc0c9cadg9n7vrg4dp1c29k2gp0
[plus.google.com] Click on the "play" arrow in the video screen in the upper left to get an Ajax video overlay. In the right column of that overlay, a list of discussed questions will appear. At the top of the list, at c20:53...
Q: Let's say a company uses product descriptions on their own site and at the same time provides the descriptions via a database to official retailers who might reuse them on their website. How can correct content attribution / ownership be ensured?
John Mueller: That's something where we probably wouldn't look into direct ownership of this content, but we'd rather try to figure out which of these URLs is the appropriate one to show for a user.
John then continues to examine possible areas of user intent... which include queries with local intent, queries with ecommerce intent, etc....
So, for example, if there's an online store that's selling a book, and it's selling it worldwide, and there's also a local bookstore that's selling the same book and on the site they have the same description as the big general online store, and if we can recognize that a user wants to find local content, then maybe we'll show them the local version.
And if we can recognize that the user doesn't want to find just local content but something maybe they can buy online, then maybe we'll show them the global version...
So it's not something where we'd say that if you wrote this product description your site will always be ranking for queries for that product description, but rather we'll try to show them the appropriate version that matches what we think the user is looking for. (c22:08)
Prompted by further questions, Mueller considers that the user might not just be looking for the product description, and that additional content beyond the product description, content like editorial reviews and user reviews, might be what the user is looking for, and that might make a difference in how Google ranks the site.
I also get the sense from questioning in the Hangout that Hummingbird's increased ability to determine query intent might be a factor here.
Note, btw, that John Mueller's answer technically covers only "syndicated" product descriptions, but I suspect the implications are wider. Mueller notes that matching the original author of a product description doesn't make as much sense as matching the author of a blog post or newspaper article.
He also clarifies that there's no "penalty" for having a dupe description, but he suggests that the ranking juice is likely to be elsewhere. He doesn't indicate whether having a completely unique description might provide a boost.
As I've discussed originality of product descriptions with clients who are manufacturers and distributors, and therefore theoretically originators, I've come to realize that there really is no way for them to determine what I'd call "essential" originality of their own marketing material. Many grabbed the online material from a brochure which might well have paraphrased other material about perhaps even competing products.
I'm guessing that tying rankings into query intent and other content on the site might not only be Google's most "relevant" way to satisfy the query... it might be the "only" way of handling the confusion of product descriptions that have built over the years.