Sally Field and Calista Flockhart by Michael Desmond/ABC
Sources confirm that Mark Perry has quietly exited his post as Brothers & Sisters' day-to-day show-runner. Perry, an alum of One Tree Hill, joined the drama this season to fill the void left by executive producer Greg Berlanti and series creator Jon Robin Baitz. Berlanti scaled back his B&S duties to focus on Dirty Sexy Money and Eli Stone, while Baitz left over creative differences. Or something like that.

Although a successor has yet to be officially named, I'm hearing that Berlanti - who is expected to take a more active role in the series - will promote from within, which should make for a seamless transition.

This is the second behind-the-scenes shake-up at an ABC Studios drama in as many days. Yesterday it was announced that Dexter's Daniel Cerone was replacing Josh Reims at the helm of Dirty Sexy Money. Reims had planned to move on after the first year to focus on developing his own projects.