Update on the research ethics of that Facebook study discussed last week: the editors of PNAS have now written an "Editorial Expression of Concern" regarding the study. Gee, guys and gals, don't you think the time to give pause and consider the Common Rule would have been PRIOR to publication? Seems like the very definition of "too little, too late" to give this very tepid, "well, YEAH, ethics and all but Facebook doesn't really have any and we all know that," explanation after every academic and his or her brother has discussed this to death everywhere, including on Facebook. I don't think this is going to help PNAS, its editors, Cornell, or Facebook come out looking any better.