However, you don't see many mainstream lesbians wearing them anymore. I think, historically, they been a symbol of masculinity and that's stereotype many modern gay women have been trying to fight. But neckties needn't conjure up images of manly-power-suit-wearing lesbians.
Instead, ties have gone beyond the boundaries of male and female, femme and butch. If anyone remembers, Avril Lavigne made ties a trendy punk staple for girls, which then evolved into an accessory for the androgynous hipster, a style of which my girlfriend is a fan. She put this set together to express one way we've seen gay girls wear ties (though most prefer jeans and a button-up).
On the other hand, I prefer the balance of a skirt with a symbolically male piece (think about it, it just dangles there).