I don't think it's ever "okay." A person's sexuality is their business, not yours, mine or anybody else's, and it's up them if, when, how and who they chose to talk to about what they like.
I agree with you NJ - when I see it in the media all it does is make me hate the show, magazine or blogger or who does it. It's the number one reason I cannot stand Perez Hilton (numbers 2-8 are irrelevant for the purposes of this conversation, as are the many reasons why I cannot stand Mario on a personal level).
I know of plenty of publicly "in" homosexuals who work in entertainment, some in glass closets and others who keep it on the DL like their life depends on it. Because their lives (livelihoods) do depend on it. For other-side-of-the-camera and backstage types like me nobody gives a shit, but for talent it's a completely different story. So when I see someone like Perez crusading like he's doing a good thing (for anyone other than himself) by dragging an actor or musician kicking and screaming out of the closet (regardless of whether they're actually gay, because I personally know at least two people he's targeted who are straight as rails) it makes me blow my top. First, who the fuck do you think you are? Secondly, you are playing a game with someone's life and career to make you feel better about yourself. I just find it to be gross, disgusting, juvenile behavior.
I think the same thing applies to friends, family and co-workers. It's their business, not mine.
But... I do agree that if the person in question is a politican, pundit or preacher who makes it part of their professional focus to demonize gay people or continue to perpetuate endemic homophobia and intolerance... those hypocritical assholes deserve whatever they get. To me there's a gigantic difference between someone like Larry Craig and someone like Neil Patrick Harris when it comes to "outing."