Megan: Questions

How common is it for people to "double up" -- eg work in publishing as agent, editor, etc., and also write/are published as an author. Thinking back to the Dan Mallory piece, I remember in it a line about, during the auction of the book, people in publishing wondering why someone in publishing would want to keep their name anonymous, which then they realized because it was Mallory and he is infamous in publishing circles. But that's made me wonder about the opposite of that, someone in publishing who hasn't made enemies of all their colleagues and rivals. Having connections has to make getting published a little easier, right? How often do people make the jump to being on both sides of the publication process?