I have a question about profile pictures. Are they moderated in some way? I remember seeing a meta post from someone complaining that their profile picture got taken down. I just saw another questionable picture on a profile that was quite similar to this one. Because of this user's reputation and amount of profile views, this made me wonder if profile pictures are moderated, and if they aren't, should they be? This could really take down the professionalism of the site. Plenty of kids use Stack Overflow, and their parents may not want them seeing things like this. Is this a problem?
OK, so here's the deal.
Why are Gravatar pictures and user names held to a higher standard than the user's profile text? Because they are public artifacts; users are involuntarily subjected to these artifacts each and every time the OP makes a post.
The profile text is different; we pretty much allow people to say whatever they want there, so long as they are not attacking someone else personally. If that reflects negatively on them, so be it; it's their profile.
It's not really about obscenity, even though obscene material is clearly not permitted. It's more about professionalism; do you really want your boss to see that scantily clad woman when he looks over your shoulder to see what you're surfing?
What's my personal opinion about the profile picture? Yum. But that's totally not relevant. What is relevant is if people start complaining about these pictures, or they become a distraction. I'm inclined to give the complainer the benefit of the doubt.
Incidentally, this same woman's picture managed to appear in a number of SE chat rooms, at about the same time, in full resolution. We removed them; I think the quagmire that such postings represent really should be self-evident. In short, we don't want to become the next "Girls Gone Wild."
Someone reported a photo once on Super User that was extremely X rated and pornographic. It's been removed, but you can check out that post for context. In that case, I agreed that it was a bit uncalled for.
But in this case, we're talking about a woman wearing a bathing suit. There's nothing inappropriate about that particular photo. If there is, then we should outlaw people from going to every single coastline in temperatures above about 70 degrees Fahrenheit, because who knows, there just might be a beautiful woman wearing a bathing suit. ;)
However, I sort of see avatars as the representation of yourself. Ideally, this would be your own photo, but a cartoon, animal, or logo would suffice just as well. As for posting photos of other people, I personally believe it sort of reflects poorly on the person who would use such a photo when that does not accurately depict him or her.
Now, if that woman is an actual photo of the Stack Overflow user, awesome. If she wants to post herself in a bikini, good for her. She rocks! But I'm more inclined to believe in this case that it's just some teenager putting up a photo of his favorite supermodel. I'm not a fan of that, because it's a bit misleading, but it's not breaking any rules, so it wouldn't be right to change the photo forcibly.
In short, if they're X rated, they don't belong (here on Stack Exchange), but in this case, if said person wants to represent him or herself as a scantily clad woman, so be it. To each his (or her) own.