>Then, there’s the dicier issue of whether an experiment like this amounts to human experimentation. It doesn’t, according to the University of Minnesota’s Institutional Review Board. Lu and Wu applied for approval in response to the outcry, and they were granted a formal letter of exemption.

I had to apply for exemptions often in grad school. You must do so before performing the research -- it is not ethical to wait for outcry then apply after the fact. Any well run CS department trains it's incoming students on IRB procedures during orientation, and Minnesota risks all federal funding if they continue to allow researchers to operate in this manner.

(Also "exempt" usually refers to exempt from the more rigorous level of review used for medical experiments -- you still need to articulate why your experiment is exempt to avoid people just doing whatever they want then asking for forgiveness after the fact)