Yes, interesting point. I skimmed through this: http://www.writersweekly.com/print/the_latest_from_angelahoy...
Related: TrustYou is doing automated semantic analysis on travel reviews across multiple sites, then syndicating their assessment back to the vendors being reviewed, http://www.trustyou.com/press/travelers-now-read-hotel-revie...
Amazon used to have an API for reviews, but it was discontinued, http://mkcohen.com/amazon-pulls-the-plug-on-review-data