First off, notice this is a local court and not directly applicable to say, BL or GR. But anyway.
A Virginia court has ruled that Yelp has to provide identifying information for seven negative reviews to a vendor who claims that they are not in fact customers of the vendor's service. If so, that would violate Yelp's TOS, and the reviews would be removed.
The reason I don't think this is too scary yet, is that book sites, as far as I know, don't have anything in the TOS that says you have to actually be a customer (or have read the book) to write a review. I can write reviews on B&N, even though I rarely buy books directly from them, and GR for instance specifically says the review space and ratings are free for all, rating on anticipation or to influence recommendations is fine.
That said, it is a precedent of sorts, and I imagine at least a couple of the loonier BBA's will be all over this, it'll be their new threat to reviewers, to take their minds off the misunderstanding what an API is (and that one can't be fraudulent). Or that negative reviews are fraudulent according to the FTC. Y'all know who I mean.