CrowdSourcing.org has released an industry report on the state of crowdsourcing. Although Mechanical Turk did not participate in this study, many of survey participants use Mechanical Turk as their workforce. You can view highlights of the report here.
Crowdsourcing.org was founded in 2010 and is a neutral professional association dedicated solely to crowdsourcing and crowdfunding.Crowdsourcing.org's mission is to serve as an source of information to analysts, researchers, journalists, investors, business owners, crowdsourcing experts and participants in crowdsourcing and crowdfunding platforms. Their website www.crowdsourcing.org offers a large online repository of news, articles, videos, and site information on the topic of crowdsourcing and crowdfunding.