In anything but the shortest of terms this is good news for Gordon Brown. What would serve Labour best is to do what the Tories did with Michael Howard: bring in an experienced pro as leader following a resignation and without contest on the understanding that they will only stay through the election and the leadership contest that follows.
It remains highly unlikely that Brown will resign. The Cabinet could, though, try and force him out. But if Harman is determined to stand, there’s no chance of a bloodless succession and the whole idea loses much of its appeal.
If Brown could be replaced swiftly and without too much trouble, it would almost certainly be good for Labour. But a prolonged and bitter leadership contest while the country is in recession, could leave Labour even worse off than it is now.