Obama is first out of the gate with a statement on the architect's departure:

“Karl Rove was an architect of a political strategy that has left the country more divided, the special interests more powerful, and the American people more shut out from their government than any time in memory. But to build a new kind of politics, it will take more than the departure of a man or even an Administration that constructed the old –- it will take a movement of everyday Americans committed to changing Washington and reclaiming their government.”"

Tailoring the response to his own larger message, obviously. More as we get them.