The appointment of Hillary Rodham Clinton as Obama's Secretary of State is interesting in all sorts of ways, but one seems especially durable. When Clinton takes office, it will be the case that three of the last four Secretaries of State are women.
This matters. Secretary of State is an immensely prestigious position. Thomas Jefferson was the nation's first; John Marshall and James Madison followed soon thereafter. The Secretary of State is fourth in the presidential order of succession, highest of all cabinet positions. Most cabinet secretaries are unknown to foreign leaders and the domestic population alike, but the Secretary of State is extraordinarily visible.
But the real point here is that the position of Secretary of State has traditionally been viewed as one possessing hard power. It requires competence with international realpolitik and a perceived willingness to make threats and compel obedience. Only two generations ago, it was common sense that no woman could occupy such a role. Now Clinton's appointment is remarkable solely because of her primary challenge to Obama; her gender is quite beside the point. The inclusion of women at almost the highest reaches of power has become normalized.
So Hillary Clinton did not get to be the first female president. But in a rather different way, she is part of the process that will eventually make it unremarkable for women to hold that position as well.