As per the LA Times' Josh Getlin & Sallie Hofmeister, two "highly placed NewsCorp media sources" say that her firing swiftly followed a Friday afternoon phone call from her Los Angeles office to a HarperCollins attorney that "included comments that were characterized as offensive." What precipitated the phone call is not completely clear, but the sources add that Regan, working in her office in Los Angeles, "blew up on the phone at a HC lawyer who had been helping the publisher handle problems with the Mickey Mantle book." Regan was then dismissed for cause shortly after that phone call by a letter faxed to her office late Friday.

More, of course, come Monday. That's when things will really get interesting.