It came up again today in conversation... should women over 30 cut their hair short? (The reasoning being that long hair is more a "young person" thing and as an older, more mature professional, long hair is just unseemly).
I've heard similar discussion about whether overweight women should keep their hair short (I'm a tich more vague as to what the actual reasoning is here...)
My own stance on this is that one of the few actual "perks" of being a grown up is that no one can dictate to you how you should wear your hair. If you're 40 and want to rock braids, more power to you. Fifty and want to die your hair neon green? As long as you won't get fired for it, what the hell? Does anyone remember Granny from the Tweety & Sylvester cartoons? Her hair was always in a bun. And you can't very well make a bun from short hair.
As long as it is clean and styled nicely, a "professional woman" should be allowed to have hair of any length she wants and not be considered less of a professional. Hell, most of the over 40 IT dudes I know have ponytails (we won't talk about their lack of hair on top of their heads).
Another nightmare for professional women is going gray... while gray hair allegedly makes men look "more distinguished" it can work against a woman. For the most part older women are generally viewed as less attractive and less productive than their younger colleagues. I've noticed in interviews that I am often the oldest person in the room by 15-20 years. I have noticed in "cattle call" type interview situations where a bunch of people show up for the interview equivalent of speed dating, that women who LOOK older (either evidenced by gray or salt-and-pepper hair or perhaps more than just a few facial wrinkles) always seem quickly eliminated. While it is certainly possible that they didn't have the qualifications, it is more likely that they weren't the "image" the employer was looking for (young, vital, perhaps "eye candy"?)
To sum up.. the colour and length of one's hair should be a matter of personal preference. We should be looking beyond what is on the outside and focusing on what skills people bring to the table. Which may be solely my opinion... and that's the long and the short of it.