I don't have very strong pro-privacy beliefs; I was unbothered when the fuss over policies mandating use of real names on some social networks was breaking. Partly this is because I believe a diversity of policies is healthy (within certain bounds), and partly because I see good arguments for and against anonymity; I've come to feel that for people who care about privacy/anonymity/pseudonymity, generally the onus to make that work is on the person who's trying to be anonymous, and that one is at least open to being given a harsh boot if violating policies over real names. If people still choose to attempt it, I'd say the consequences are upon them and very little more. If people bother to poke around and unmask those people for whatever reason, that's generally ok. This goes for all kinds of identities and privacy objects, generally speaking, and there are a lot of circumstances where I just am not interested in taking a stand.
I say that in the general case because while I believe that public-oriented speech should be given a very, very wide berth (in the legal and social-approval senses) even when offensive, interpersonal speech ; directed at a specific person, merits less protection. Harassment is almost exclusively interpersonal and reasonable (if difficult in drawing firm lines) to regulate (either culturally or legally). There should be more consequences for being conversationally aggressive with a person (even if not legal ones); we judge someone who goes out of their way to jab at a person's identity differently than someone who jabs at a group. There are additional possibilities for viciousness in interpersonal interaction, plus western society operates under the ideal that we should accept that others won't validate our various identities, just see our humanity and tolerate us.
In general, outing people (name, sexuality, whatever) should, in my view, not be considered acceptable if it puts someone in reasonable harm in the immediate-to-short term that they're making continual effort to avoid, and provided they're themselves not acting in a particularly malicious way to specific persons. Otherwise, even if it makes life more complicated, I think it's fair game (but potentially douchey) to do so. There are circumstances where that immediate-to-short-term harm might be present for a long time, and I am sympathetic to such cases. I believe that the site of judgement is not with the person with the secret though; one should not need to take their word for it, but rather to make a reasonable effort to judge circumstances; this is admittedly not a watertight process, but the weight of errors in judgement also fall on the person exercise judgement; it is not enough to really dislike someone to decide their safety concern is not legitimate, and if one cannot fairly judge that, it is safest to default on the side of safety. The reason I would not go with the secret-holder's judgement is that often personal preference or other not-externally-actionable reasons for secrecy taint their judgement and claims.
One area I'm not entirely certain about (but right now I'm leaning towards finding okay) is whether social network operators should be comfortable using out-of-bounds means to out people. This came up recently where an online troll on Gawker was outed by Gawker staff. Michael Brutsch, a middle-aged Texan man, found himself outed, socially shunned, fired, and uninsured in a very short period. I largely agree with Jezebel's analysis.
I am reminded of more marginal trolls like Kinsey Hope and some other third-wave activists who use sloppy logic and inappropriate language for a distorted version of legitimate social concerns; they're clearly on the other side of the line, in that most of them are not harassing or interpersonal in their trolling (although the SJ community does have its share of trans activists who have harassed anyone who doesn't use their preferred gender theory to the point where some of the victims have been chased off the internet for awhile, alongside anyone who might imply that being fat is a bad thing (and hey, by the way, all other things being equal, it's healthier and a lot more attractive to be a middling weight/body shape than being well over or under that, and if you feel oopressed by that, my response is best summarised here, which is not to say that I hate fat people, just that it's a negative attribute among a variety of attributes that people can have); I would be comfortable with outing the harassers in such cases for the same reason the people who make threats generically against feminists at conferences should be outed).
One of the areas where I am still working my thoughts out is whether there should be criminal consequences for harassing someone over a long period of time into suicide. It's one thing (that I'm very comfortable with) to have the law being able to react to harassments with "cut that shit out or there will be legal consequences". I am also very comfortable with programmes to help support harassment victims and help them be aware of their options as well as generically discourage harassment. I'm not sure what to think about cases where there never was involvement with the law, and were I to decide I'm comfortable with action, making firm lines suitable for legal incorporation would be damned hard. Someone who is mentally unstable who gets treatment that's within the bounds of normal interaction (or even moderately rough treatment) who finds that the straw that breaks the camel's back and goes home to kill themself; that last straw should probably not be actionable. Would egregious harm-from-words that deeply creates the vulnerability and isolation that causes one to suicide be more actionable? What kind of standard of self-care should we expect a reasonable person should assume other people apply to themselves? Legally or even socially, it's a really hard problem, and one I'm reluctant to have the law step into. Social judgement might be more comfortable with softer lines because it's done by people working in personal mode, but even there errors and misjudgement are possible; yet in social judgement we can easily recognise "whoa this is totally excessive, this person is a top-grade putz even if I can't draw a binary boundary or a three-part test as to why" type things.
In the meantime, I hope that we can rely on other means to lessen harassment; it would be nice if we can mostly eliminate the problem of bullying through use of good institutions and social support without trying to prosecute it.