During the Mediawiki Architecture Summit there was a break-out session about new ways of editing and improving the API
One thing that came up was the section on Captchas being considered harmful
This ticket is the suggestion to turn captchas into actually useful micro-edits, like the classic reCAPTCHA (http://en.wikipedia.org/wiki/ReCAPTCHA) did with scanned images. this could be a number of different things, image editing/cropping, OCR (commons to wikisource), or edits as currently developed by WikiGrok.
For example you could first show a Wikidata item without an "instance of" to a number of users and let them decide if it's a person or not. Then once some data has been gathered you could use the same question as a captcha and check against the previous answers you got.