I am in Minneapolis right now, at the Gay and Lesbian Task Force's annual conference on Creating Change (www.creatingchange.org) and everyone has name tags, as you would expect at a conference. The cool part is that many individuals I've met have written their preferred pronouns on their name tags. This is really cool, since many people here, especially in the transcended hospitality suite where I've spent the majority of my free time, are somewhat androgynous and nobody wants to get pronouns wrong.
The thing is, people outside of the queer bubble are not nearly as aware of the importance of correct pronouns and gender identity. See, if your body matches your brain it doesn't matter as much when someone assumes that you're the gender you are but for people who identify as trans*, gender queer, or other it can hurt or at least be uncomfortable to be misgendered based on someone's perception of who they are.
So, how do you know? Well, without asking or looking at someone's name tag at a lgbt conference, you don't. Never assume anything when it comes to gender, even people who present themselves one way may identify differently. Think about it, you wouldn't want someone to assume that you're a different gender than you are, right?
What pronouns do you prefer?