As the number of creators of geekery - comics, sci-fi pulp, fantasy novels, etc. - expanded to include women, I'd definitely say that it's gotten female-friendlier.

As best I recall my pop culture history studies, a lot of the early scifi/fantasy was dominated by male writers and artists, which tended to pander to male tastes (Dejah Thoris, anyone?). When the markets expanded in the 50s and 60s to include women creators like Le Guin (and even Trek pulp by Diane Duane), you saw some shifting to more gender-complex materials. The comics industry in particular over the last 15 years has seen more women as artists and writers, which is where I think more of the female-fan-friendlier stuff has been happening.

I'd still say it's 70/30 male/female orientation in the geek markets, but it's getting there.

As a Late Gen X Geek Girl who's hung out with geek boys ever since she found a critical mass of them in high school/college, and who's been married to a geek for almost 10 years, I would say a "qualified yes".

Yes, because geek males worth knowing are more welcoming to/interested in an intelligent gal who gets their jokes, understands what he did at work/school that day, embraces/shares the social quirks that made their formative social lives miserable, and can match them zing for zing. Also Yes because of the trends in Geek Pop Culture mentioned above by Paul. Finally, the male/female ratio in geekdom is rather skewed, but more so these days because many younger girls hide their lights under bushels to fit in, and get sucked into conformity. That in turn makes the straight geek girl highly prized as a friend or companion in geek culture, at least to men with taste. (and is there any other kind of man worth knowing, geek or no?)

Qualified because, well, let's be blunt--even the best geek males can be diamonds in the rough into their late 20s. Guys mature slower than ladies as a rule, and geek guys even more so, for a variety of reasons. Many geeks of my acquaintance really don't think they mastered adulthood until their late 20s. On the flip side, geek girls tend to mature at about the average speed, if not faster. Also, there are incurable male doofuses in every IQ bracket. I dunno if there are more of them in geekdom, so much as they don't have the social know-how to keep it roped in at first. Of course, The definition of "geek" I use includes the ability to interact with a female on an equal plane, however awkwardly. Any guy worth knowing, geek or no, has learned or will swiftly learn this skill.

I think geek girls have to make their own path in geek culture, and that sometimes there are obstacles or stupid misconceptions to be dealt with. However, I think as a rule the intelligent female has a MUCH harder time of it in 'mundane' society, and that the Geek subculture is getting more female-friendly by the day.

I dunno but most of my tv heroines come from "geek" culture - Scully, Starbuck, Ro Laren, etc

As someone who has been trying to make a go of it as a SF/F writer, I have to say yes. If I was the kind of guy who didn't respect women's professional opinions, I'd be in a world of hurt dealing with editors, agents, and fellow writers, given the numbers of them who are women. Sexism in the publishing world mostly comes from the sales guys, who are usually more interesting in the marketing side. You know, the sort of guys who cancel "Firefly" or are neutering the SF channel; they are not geeks.

This is not to deny the clueless sexism on the part of some men mentioned above, but rather to point out the oppertunities for women in geek culture.

I don't think geek culture is particularly anybody friendly. In many ways it accepts all because it holds almost everything with the same level of self-critical disdain warring with obsessive love. To paraphrase Kevin Smith (badly and from faulty memory) geeks are the only people who will show up to a convention wearing a replica stormtrooper costume, run into a guy wearing a perfect Spock costume and deride him for being a fucking nerd with a straight face.

You must be willing to defend your passions and in return you will be instantly accepted by anyone else who shares them. And if you can't stand the heat you will not be very welcome.

I happened across this a while ago:
http://girl-wonder.org/girlsreadcomics/?p=202

It's all about sexism at comic conventions. There was more crossblogging about it somewhere else, but I can't remember where (some sites seem to have moved).
I saw something similar about game conventions a few years back as well, but E3 has toned down their hollywood aspects for one.

I'm not sure if it relates to the question specifically but the crux seems to be that if you get models dressed up in tight and minimal clothes whose job it is to be nice while putting up with lustful attention (or even encourage it), this environment gets at least a subset of males thinking it applies to every girl there is at the event. This we can state with some confidence. That then might discourage females from turning up and so forth.

There was a bit of a dust up a while ago over at Scienceblogs and in the Skeptic-o-sphere in general over how male dominated and faintly boys club the whole thing can be, particularly at conferences and other get togethers (there was one set of talks in particular used to illustrate that the speakers were only talking to the men in the audience and making lad-ish jokes etc. I can't remember which one. But these are old academics we're talking about, not maladjusted fifteen year olds or whatever). From memory there was some overlap with debate amongst the female contingent over how brassy and crude (or, as I would term it: funny) and even underdressed some of the girls are and whether or not that was bad for females in skepticism etc etc. So that one's still around too.

It's still very much a hot topic that will flare up from time to time, is all I'm saying.
It's hard to say for sure but much of geek culture strikes me as some of the worst encalves of male stupidity and the most alienating to women. That could be just because it's what I know, but I think you'd have an easier time if you were a female metalhead or gearhead than sci-fi fan or whatever.

I think that depends a lot on what you think geek culture is. Some folks seem to think that's university engineering departments and others think it's what gets sold as geek collectables or whether video games are cooperative. What I think of as geek cultures is different enough than what someone else thinks of as geek culture that we'd probably have to start by defining terms.

But all in all I think there are great people and jerks to be found in most environments. If some fan boy gets rude when a girl or woman is around that's on him and not the group he'd like to think he has some kind of status in. It's not because he's a geek. It's because he's a jerk.