I've talked to a few women who've said that they fear they won't be taken seriously as computer professionals if they dress in a "girly" way. I used to think that I was immune to that fear. But two weeks after my job started at GrammaTech, I looked at my closet and pushed everything I'd worn in the last two weeks to the left and everything I hadn't worn to the right. On the left were jeans and t-shirts and gray and black and brown. On the right were dresses and bright green and bright blue and pink and floral prints. I was very surprised. I took a picture of what it looked like so that I wouldn't forget.
I realized that what I thought my clothes looked like, based on what was hanging in my closet, was completely different from what my clothes looked like to other people in practice. I clearly liked the dresses and the floral prints and the bright colors, or I wouldn't have had them in my closet -- but I wasn't wearing them, because on any given day, they seemed like the wrong thing to wear. I realized that I feared not being taken seriously by my co-workers if I wore floral dresses to work. I decided to call bullshit on that. After all, as Kathy Sierra points out, the compiler doesn't care what you're wearing.
Of course, there are a lot of women programmers who choose not to wear girly clothes because they don't want to wear girly clothes, not because they're afraid to do it. And a lot of the time, that's me. In 2008, when I was living in Portland, someone I knew was hesitant to wear her preferred everyday outfit, a skirt, to OSCON out of concern about not being taken seriously by people there. Eventually, she did wear the skirt, and a friend of hers congratulated her on being brave enough to wear the clothes she liked to wear. I remember standing there listening to their conversation and feeling rather irked. I, too, was at OSCON and wearing the clothes I liked to wear, but because my clothes happened to be a t-shirt and thrift-store sneakers and jeans, nobody seemed to be congratulating me. It made me wonder, briefly, if I was less brave than the woman in the skirt -- or if anyone at OSCON was concluding from my clothes that I was less brave. In retrospect, I don't think anyone was. Bravery is extremely personal. One person's brave act could be a neutral or cowardly act for someone else. And certainly the idea that one's bravery can be determined from one's appearance is completely senseless.