This is probably getting away from the IRB focus, but Lior Strahilevitz, a legal scholar, had a good article a few years back entitled "A Social Networks Theory of Privacy", suggesting some ways to think through the discomfort which many -- rightly, I think -- have with seeing public/private applied as a binary distinction to speech: "This paper argues that insights from the emerging literature on information transmission through social networks can help courts develop a more rigorous and objective notion of 'privacy' for the purposes of the privacy torts. It argues that privacy tort law should not focus on the abstract, circular, and highly indeterminate question of whether a plaintiff reasonably expected that information about himself would remain 'private' after he shared it with one or more persons. Instead, the law should focus on the more objective and satisfying question of what extent of dissemination the plaintiff should have expected to follow his disclosure of that information to others." cheers Bram