I gave it several of my old Staff Reports, and almost all of them correctly came up male (the one exception being What can I do to prevent static shocks?).
I’d be interested to see what it would do with a sample from James Tiptree, Jr., but not enough so to dig up a book and type in 500+ words by hand.
3 out of 4 judged to be male. Which really amuses me, since I tend to write very florid prose.
The one it judged female was a rant about feminism, so I think that was a gimme. 
No, I’m not male.
Well, she certainly had the SF community fooled, but then she WAS writing SF (when there weren’t many females in the field). I remember one old intro to one of her books or anthologies, wherein the writer declared that old JT was a man’s man, a guy who positively oozed testosterone. I think it was Silverberg, not sure now.
I think it’s interesting that the feminine pronouns are associated with female writers. It seems to imply that, empirically, men rarely write about women.
I fed a few paragraphs of “Painwise” by Tiptree, and
Apparently, I am male. Ironically enough, in light of Harriet the Spry’s observation, I gave it a snippet from a conference paper on women in Elizabethan popular ballads, and it still got it wrong 
First three I submitted, I was female (which I was a little surprised by, as the first submission was of a very technical nature, which I thought would be judged as “male”.) Next three I submitted, I was decidedly male. Last one I submitted, it was male by a score of 1153 to 1152. So, doesn’t really work better than a coin flip for me.
edit: Well, I finally found a 5000+ word block of fiction from years ago, and it got me right on that one:
And masculine pronouns don’t count at all, which is even more interesting.
I fluctuate wildly between being pronounced male or female. But in general the genie pronounces me a bloke (nup!) every time I talk about my kids. Two of whom are girls…
So apparently one’s femininity is determined by family composition. Or men never talk about ther kids, of course.
A few months ago I edited an article about the application of Title VII to transsexuals, written by a male-to-female transsexual. I pulled out a couple random paragraphs from that article and plugged it in.
Result:
Hm…
So then I plugged in a few paragraphs from my article about voter fraud, and it came back:
So it dinged me pretty good. ::struts::
:smack: that should, of course, be EXCEPT when I talk about my kids
According to the Gender Genie, “ballsiest” is apparently gender neutral. It was not coded in the analysis.
Wow! This this really works!
On the edge tipping toward male by 10 % in almost all cases. It makes me feel all metrosexualish.
Well, yeah, except that it judged the writer as “male” for a piece of text where I repeatedly refer to myself as a woman.
I tried a lot of my long message board posts, which came up male so consistently that the one that didn’t sort of surprised me.
Huh. I wonder why it distinguishes between “Fiction”, “Non-Fiction” and “Blog Entry”. It didn’t seem to make a difference in the results.
Combining elements of all three (OK, very little non-fiction), I wrote this series of blog entries of over 500 words. For all three categories it rated it as Female/Male = 687 / 473 (Female!).
I threw in a chunk of my most recent fiction, main character is a 10 year old boy. It came back:
Words: 1970
Female Score: 1810
**Male Score: **2528
So maybe this means I’m writing his voice very well? I dunno. I threw one of my blogs in there and:
Words: 2422
Female Score: 2594
**Male Score: **3087
I guess I just write like a man. Or maybe I use the word “the” too often as, apparently, that’s a male word.
Weird. And inefficient.
Let’s try this again:
I like to lift big weights what my big he-man muscles. Then I like to sweat as a pig more scarf down a bucket of ribs before letting out a huge honkin’ fart. You know, the kind of fart that lasts three minutes as makes many dog leave the room. Then I like to boink a few Hooters girls before heading out to play golf around many dudes. Then these dudes head off to the bar to do some shots as hit on chicks. Later on, who take a tour of many construction sites to boast about how many could build whatever it is even better.
Female Score: 0
Male Score: 310
The Gender Genie thinks the author of this passage is: male!
It doesn’t make many sense now, but it many has testosterone.
As to how it works, these two professors, Moshe Koppel, professor of Computer Science at Bar-Ilan University, and Schlomo Argamon, currently professor of Computer Science and Director of the Linguistic Cognition Laboratory at the Illinois Institute of Technology did a study looking at the differences in language choice between male and female fiction authors. For instance, they found that women were more likely to use more personal pronouns in their writing, while men were more likely to use more determiners, words like “a” and “the”. They refined their algorthym, and were able to come up with one that could determine the sex of authors with about an 80% accuracy rate.
The website bookblog read about their studies and came up with a dumb downed version of the algorthym which isn’t really effective at all, and they created the Gender Genie.
If you’re interested, here’s the original paper:
A future version of the algorithm will correctly identify “wildly overcompensating latent homosexual” male authors.
I am not a wildly overcompensating latent homosexual! And if you say I am, I’ll kick your ass with a really fabulous pair of cowboy boots with a matching belt, fella.