I ran across this last year, posted it on Corner and forgot about it until a link to that post came up in the stats. At the time, I ran several entries from Tangents and it decided I was "male". The site notes they believe they have an 80% accuracy rate. Running it again today (using several entries at once), the results are similar. Just for kicks I ran a few posts from blogs I frequent where I know the gender of the writer. It was accurate for them.
This is based on some published research about gender and writing styles with some speculation about a variety of causes and results of the differences. I first ran across those studies referenced at either Butterflies and Wheels or Arts and Letters Daily. If later I turn up the research I downloaded, I will post the journal references.
Check it out yourself at: The Gender Genie
Words: 621 (NOTE: The genie works best on texts of more than 500 words.)
Female Score: 860
Male Score: 1314
The Gender Genie thinks the author of this passage is: male!"