I think it's pretty well known that JK Rowling is a woman. Also, she has recently written some books under the pen name "Robert Galbraith".
Edit: I see above that the poster was referring to Notch. Just a simple case of an unclear antecedent (and being unfamiliar with Notch's and Rowling's recently releases ;) )
Interesting note, if an author uses a pseudonym of a different gender, its appropriate to use that gender of the pseudonym. I find it weird that James Tiptree, Jr. is still a "he" when we've known for decades it was Alice Bradley Sheldon's pen name.
In fact, Tiptree, not Sheldon, has been inducted into the science fiction hall of fame, which is even weirder.
I don't think I've ever met anyone - in real life or in the UK educational system, anyway - who referred to George Eliot as being a "he" without instantly being corrected.
Edit: I see above that the poster was referring to Notch. Just a simple case of an unclear antecedent (and being unfamiliar with Notch's and Rowling's recently releases ;) )