A few libraries so far have reported that spam-bots have been creating accounts on their site and attempting to submit book reviews. (As you know, the Book Review feature can't be used for spamming, because librarians must approve any post before it goes public. Nevertheless, the spam-bots keep trying. :-)
The BookPoints app has a "reCAPTCHA" option that we can enable to help prevent spammers from creating an account. (This is the feature you've probably seen on other websites where you must click the picture of motorcycles or storefronts to confirm your humanity.)