Mysterious Author Unmasked

In case you haven't heard, JK Rowling (author of the Harry Potter series) wrote a mystery book under a pseudonym, it's pretty good, it's now soaring up the charts, and another mystery is in the works. Not surprisingly, she says she had hoped to remain anonymous for a little while longer. So who figured out that "Robert Galbraith" was really she ~ and how? It took a little high-tech detective work: http://www.bbc.co.uk/news/entertainment-arts-23313074