Here is a woman in a dress, something she might wear to convention about programming if she wanted to wear a dress: http://dressforweb.com/wp-content/uploads/2014/05/Korean-ver...
It's fairly modest and not loudly styled. This is not the same style of dress as a man wearing a suit. The equivalent for a woman would be this:
http://www.acrdepos.com/wordpress/wp-content/uploads/2013/06...
or this, if you wanted a dress:
http://juegoskizi2.com/wp-content/uploads/2014/04/skirt-suit...
I do not thing most women would have an issue about assuming they aren't a programmer (any more than a man in a suit) wearing either of those two last things I linked.
You might say that it's loudly styled, but somehow this guy never has people doubting his programming cred: https://www.google.com/search?site=&tbm=isch&source=hp&biw=1...
I was taught (and coached) that no matter what kind of job you're interviewing for, you should show up in a suit and tie. Not because you ever expect to wear that while working, but because it is considered a show of respect to the interviewers.
In any case, the point here is that men's reactions to women in dresses often cause distress and make women feel uncomfortable in technical settings. That's frankly ridiculous, since (as far as I understand) many women like to wear dresses and don't feel that they're formal. Maybe it's due to a misunderstanding? Men labor under the misapprehension that dresses are formal attire when they're not, and that causes the disconnect, etc. etc. Doesn't mean we should just accept it -- let's correct the misunderstanding. :)
Anyway. Maybe it's worth asking the women you know.