Yeah Dave-o, you're right that I DM. My group has one female player and three males right now. When I DMed online a few years back, there were two female players and six male.
Does it change the group dynamic? Hmm. Well, since by definition I can't play in an all-male group, I guess I couldn't say.

But I've played in games that had male DMs and female DMs, and actually, the women seemed *more*bloodthirsty, if you ask me. Every male DM I've played with was obviously (to me, at least) trying to keep the party alive regardless of their stupidity. The women were just downright evil, let me tell you. No quarter.
All the people I presently play with are into both role playing and combat. As a DM, I think I can tell a reasonably good story, but I think I might actually be better at the mayhem. I'll have to ask my players what they think.
One thing that is harder for women, IMO, is finding a group to play with. Women aren't generally comfortable answering ads to play with complete strangers. There's a personal safety issue we are always thinking about that guys don't have to deal with. For example, I saw a post on the Wizards boards for an RPGA group in my area that is looking for new players and DMs. Since I'm pretty much self taught, I've been thinking about contacting them. I'd like to see what more formally trained DMs are like, and I'd certainly like to meet some other local players. But I'm pretty nervous about putting myself in a potentially scary situation. I answered an ad one other time, and the guy was just a complete freak. Fortunately my husband was with me, but I'd rather not do that again, and my husband really isn't interested in playing in another game.