For the purposes of this discussion, consider the following scenario:
You have written a fair amount of quality, unpublished content that third-party websites wish to license from you and white-label on their own sites (i.e. you are ghostwriting for these third parties). In other words, there will be no attribution or links referring to your name, email address, or website at all; it will appear to readers and search engines as if the article were written by the third party instead of by you.
Consider that 10,000 of these third-party sites were created independently, without any association to each other (they are absolutely NOT part of a blog farm network). From your collection of 100 articles, you plan to license the white-label publishing right of each article to 100 of these sites (again, on a per-article basis). So, while each of your 100 articles will be published 100 times, it's fair to assume that no site will host all 100 articles. The most any one site will host is 30 articles.
Now for the question: Given this scenario, and that your intent is not to game search engines at all (but rather to provide quality content on established websites), do you need to include "no-index" meta tags on the pages that display your content?
Clearly, you wouldn't want your customers to receive the wrath of the Google Duplicate Content Penalty. However, at the same time, if they can benefit from any Google juice deriving from your content, then that would be a nice benefit.
I suppose a more concise question may be, "Would this behavior cause Google to penalize the third-party websites? Or, would Google simply choose one of the sites as hosting the "best" version of the content on a per-article basis?"