How have women really voted these past twenty years? In general Democrats tend to capture the vast majority of African-American women voters, single women, and economically vulnerable women. White married women, especially those with children, tend to slightly favor Republicans, while more traditional homemakers and evangelical Christian women have been firmly in the Republican camp.
Though single women in the past have not come out to vote in force, if they did turn out for Hillary in 2008, that could give her an over-the-top boost in some key states.
I always laugh at the idea that women, even a subset like "single women", are a monolithic voting block, and Blyth seems to share my cynicism. And here's something that's been true as long as I've been voting: Neither party cares about single heterosexual women without children (although the Dems make an exception for women who wish to remain child-free by killing their unborn). Democrats are all about the single mother, especially the low-income or minority single mother, and lesbians of any relationship/child status; Republicans are all about the married women, especially mothers.
I throw in with the GOP because they're less ideologically committed to taking my earnings away, and more committed to keeping America from being destroyed by Islamofascists. But it's uneasy. All the "couples this, families that, marriage this, children that" rhetoric wears on me. "Parents should be allowed to use their money to raise their families as they see fit"--I don't disagree, but why shouldn't I be allowed to use my money as I see fit, instead of how Hillary sees fit?
Back to the point, it doesn't have to be a foregone conclusion that "all single women will vote for Hillary in 2008." But the GOP needs to make more of an effort to include the old-maid aunts of The Children.