"Research shows that sales and profits go up when we make girls' toys pink."
"Okay then, make girls' toys pink!"
Anyway, my guess is that whatever strategy would encourage the majority of women to go into programming isn't necessarily something women on hacker news would like, because women on hacker news are part of the self selected minority who already buck gender trends. You don't need pinkification because, if you were the type of person who did, you wouldn't be here.
I'll just note that some of us who might have been most attracted to the profession would be turned off by pinkification, and that we may be harder to recruit into recruiting efforts that we perceive as ghettoizing. I quit a women's organization dedicated to a specific technology because all the meetups they organized seemed to be oriented around manicures.
Someone mentioned above that law and medicine have evened out (or even begun to invert) their gender ratios over the past generation. They didn't do that by pinkifying the profession - by giving little girls pink stethescopes or gavels. They did that by changing expectations of who turns out to be a doctor or lawyer - the expectations of both children who hadn't yet chosen their profession and of the adults who guide their choices; choose whether to admit them into study programs; and eventually hire them.
You touched upon something that's critical to the whole issue: the perception of traditionally female stuff as inferior. The feminist movement has come a long way getting women through the door and into traditionally male-dominated fields. What still remains as an enormous challenge is the elevation in status of traditionally female roles and norms.
For as long as we think of silver and black and blue as high status and pink and purple as "ghettoized", we have a problem. Just as we have a problem that nursing and teaching are low status compared to other professions.
For as long as we consider care work to be inferior to business work, women will never be truly free.
For reasons that I'm not even going to attempt to speculate upon, a non-trivial number of young girls really like that stuff. Pretending it's not true, or casting judgement on the morality of this won't change the fact that it's effective. If it helps spark children's creativity, imagination, and passion for building things, then that's great in my book.
And talk to them about it. If they're hearing one thing from their friends and another at home, they will experience cognitive dissonance, and they will wonder about it, even if they don't know to ask about it.
Edited to add: pinkification and genderization of toys seems to have accelerated since I was a kid. Entire aisles of toys in pink boxes instead of a single shelf of barbies. The explosion of Disney princesses hasn't helped either. (I remember being a teenager going to see The Little Mermaid and my mom explaining that it was a big deal because it was Disney's first animated feature in decades.)
I think maybe to some degree people are subconsciously frightened that women are now able to wear anything men can wear, do anything men can do. The reaction is to make sure that there are still differentiators between men and women (because, OMG, how can you interact with a person without being able to define you understanding of them based on gender? [never mind that we do it all the time in places like HN]) - and the easiest way to do that is to make sure the girls are pink! That way you can tell them apart!