LabourList editor Mark Ferguson is quitting after five years at the helm:

“Editing LabourList for the past five years has been a huge honour. And although it is time to go, I will miss LabourList – and its readers – a great deal. But I’ll still be reading the morning e-mail and dropping by LabourList each day to see what’s happening in the Labour Party. Just like everybody else.”

To work on whose campaign?

UPDATE: A source says to expect an announcement tomorrow, and more pointedly that Mark is on good terms with most of the Labour leadership contenders.